Follow-up to #9669 addressing the Copilot review feedback on the regression fixture: #9669 (review)

## What

The `#9651` regression fixture had `src/dyn/b.js` import a named `z` from `../zod/external.js`, but `external.js` never exports `z`. That import was only valid because the fixture enabled `shimMissingExports`, which is unrelated to the bug under test. The binding is never used — only the `b.js → external.js` import **edge** matters (it pulls the wrapped `external.js` into the dynamic-import chain).

This PR:
- switches `b.js` to a bare side-effect import (`import '../zod/external.js';`), so the fixture is semantically valid without missing-export shimming, and
- drops the now-unnecessary `"shimMissingExports": true` from `_config.json`.

## Why it's safe

- The bundled output is **unchanged** — `artifacts.snap` does not move.
- The fixture still reproduces the original panic on the pre-fix commit: I checked out `5cfff49` (the commit right before #9669 landed), dropped in this updated fixture, and it still panics with `"init_external" is not in any chunk`.

Test-only change; keeps the regression focused on #9651.

Address the review feedback on #9669: `src/dyn/b.js` imported a named
`z` that `external.js` never exports, which only worked because the
fixture enabled `shimMissingExports`. The binding is unused — only the
import edge matters for the repro — so switch it to a bare side-effect
import and drop the now-unnecessary `shimMissingExports` option. This
keeps the regression focused on #9651 without relying on missing-export
shimming. The bundled output (snapshot) is unchanged, and the fixture
still reproduces the original panic on the pre-fix commit.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

## Summary

Follow-up to the review nit on #9669: when a wrapped ESM module tree-shakes down to an
empty body, rolldown still emitted a no-op call to its `__esm`/`__esmMin` wrapper, e.g.

```js
function en() { return "en"; }
__esmMin((() => {}))();   // ← dead weight: empty closure, calling it does nothing
```

This PR marks such no-op init calls `@__PURE__` so the default `minify: 'dce-only'`
pass drops them (and, once the wrapper is unreferenced, the wrapper declaration and the
`__esm`/`__esmMin` runtime helper too).

**Before**
```js
var __esmMin = (fn, res) => () => (fn && (res = fn(fn = 0)), res);
function en() { return "en"; }
__esmMin((() => {}))();
```
**After**
```js
function en() { return "en"; }
```

It also collapses the `require(esm)` sequence form `(init_x(), __toCommonJS(x_exports))`
→ `__toCommonJS(x_exports)` via the same mechanism.

## Approach

1. A small generate-stage pre-pass, `compute_init_is_noop`, flags wrapped (`WrapKind::Esm`)
   modules whose `__esm` closure body is provably empty — every top-level statement is a
   hoisted function declaration or a source-less export clause, so nothing lands inside the
   closure. The classification runs in parallel (`par_iter_enumerated`).
2. The finalizer sets `pure = true` on the init `CallExpression` at the three emission sites
   when the callee module is flagged; `dce-only` does the rest.

The classifier is deliberately conservative (a non-qualifying statement only ever *keeps* a
redundant init call — it never drops a needed one), and a `debug_assert!` in the finalizer
cross-checks every flagged module against the *actual* `stmts_inside_closure`, so any
misclassification fails loudly across the fixture suite. Guards exclude shimmed missing
exports (their `x = void 0` lands in the closure) and concatenated wrapper groups.

## Out of scope (kept on purpose)

The empty inlined dynamic import `Promise.resolve().then(() => Object.freeze({ __proto__: null }))`
is **not** removed — Rollup keeps it for `import('./empty.js')` of an empty module, so it's
Rollup-equivalent and stays.

## Why the detection lives in its own pass (and not elsewhere)

The flag is consumed **cross-module** — an importer marks `init_importee()` pure based on the
*importee's* status — which constrains where it can be computed.

### Not in the link stage (`cross_module_optimization.rs`)

That pass runs **before** the two inputs the decision needs even exist:

- **`is_included`** is produced by tree-shaking (`include_statements`), which runs *after*
  `cross_module_optimization`. A module that's tree-shaken away has no init to reason about.
- **`concatenated_wrapped_module_kind`** is assigned during the generate stage's
  chunk/concatenation analysis. We must restrict the optimization to standalone wrappers
  (`ConcatenateWrappedModuleKind::None`): in a concatenated group the shared `init_*` runs the
  *whole group's* closure, so one module's empty body wouldn't prove the call is a no-op. That
  isn't knowable before chunks are formed.

Folding it here would force the decision with incomplete information (pre-tree-shaking,
pre-chunking).

### Not in the finalizer (`module_finalizers/`)

`finalize_modules` runs the per-module finalizers in parallel (`par_iter_mut_enumerated`):

1. **Immutable borrow** — the finalizer holds `&LinkingMetadata` / `&LinkingMetadataVec`
   (`ScopeHoistingFinalizerContext`), read-only, so it *cannot write* the flag mid-pass.
2. **Determinism** — even if it could, an importer finalizing concurrently with its importee
   could read a not-yet-computed (default `false`) value → non-deterministic `@__PURE__`
   placement → flaky snapshots.

So the flag must be settled as a barrier *before* finalization begins.

### The fit

The pre-pass sits in the generate stage **after** tree-shaking and chunk generation (so
`is_included` and `concatenated_wrapped_module_kind` are known) but **immediately before** the
parallel `finalize_modules` (so every importer reads a settled, deterministic value).

## Testing

- Updated 5 fixture snapshots (incl. the #9651 regression); each remains runnable.
- Full `rolldown` + `esbuild` integration suites pass; the `init_is_noop` debug-assert holds
  across all ~1.6k fixtures.
- `just lint-rust` clean (clippy `--deny warnings`, fmt, `cargo check --all-features`).

## [1.1.1] - 2026-06-11

### 🚀 Features

- ecmascript_utils: introduce AstFactory for AST construction (#9682) by @hyf0
- drop no-op init calls for empty wrapped-ESM modules (#9678) by @IWANABETHATGUY

### 🐛 Bug Fixes

- resolver: honor package.json#type for .jsx/.tsx extensions (#9690) (#9699) by @IWANABETHATGUY
- hmr: report the full-reload reason for the invalidate-loop case (#9708) by @hyf0
- explicit `moduleSideEffects` from a hook must take priority over the `package.json#sideEffects` (#9688) by @sapphi-red
- keep the `rolldown-runtime` name for the standalone runtime chunk (#9685) by @shulaoda
- lazy-barrel: request all exports for entry barrels on first encounter (#9672) by @shulaoda
- finalizer: skip init_*() for tree-shaken wrapped ESM owners (#9669) by @IWANABETHATGUY
- order `chunk.imports` by execution order (#9654) by @chuganzy
- vite-resolve: preserve slash separators for Sass partial exports (#9546) by @cjc0013
- cross-chunk CJS wrapper shadowed by author-local binding (#9648) by @IWANABETHATGUY

### 🚜 Refactor

- precompute wrapped-ESM init metadata in generate stage (#9712) by @IWANABETHATGUY
- ecmascript_utils: fold construction ext traits onto AstFactory and delete AstSnippet (#9702) by @hyf0
- finalizer: finish ScopeHoistingFinalizer migration to AstFactory (#9701) by @hyf0
- finalizer: migrate module_finalizers/mod.rs to AstFactory (#9700) by @hyf0
- hmr: migrate hmr finalizer to AstFactory (#9695) by @hyf0
- plugin: migrate vite_build_import_analysis to AstFactory (#9693) by @hyf0
- scanner: migrate tweak_ast_for_scanning to AstFactory (#9683) by @hyf0
- always split runtime module first (#9419) by @IWANABETHATGUY

### 📚 Documentation

- tsconfig: correct auto-discovery resolution to match TypeScript (#9714) by @shulaoda
- design: plan to unify all internal AST construction (#9673) by @hyf0
- tsconfig: align reference resolution docs with TypeScript behavior (#9641) by @shulaoda

### ⚡ Performance

- avoid per-module join Strings in scope-hoisting concatenation (#9645) by @Boshen
- avoid intermediate Strings in the ESM export clause (#9644) by @Boshen
- reuse a scratch buffer for facade namespace names in the scanner (#9642) by @Boshen
- reuse the import-matching tracker stack across named imports (#9643) by @Boshen
- avoid cloning the per-chunk export-items map in render_chunk_exports (#9639) by @Boshen
- avoid CompactStr allocation in sorted-exports membership check (#9640) by @Boshen

### 🧪 Testing

- add more `moduleSideEffects` precedence tests (#9689) by @sapphi-red
- 9651: drop shimMissingExports from regression fixture (#9674) by @IWANABETHATGUY

### ⚙️ Miscellaneous Tasks

- update react repo links (#9711) by @iiio2
- remove outdated pnpm configurations (#9666) by @btea
- deps: update github actions to v2.81.5 (#9665) by @renovate[bot]
- testing: migrate test harness off deprecated inlineDynamicImports (#9710) by @IWANABETHATGUY
- hmr: delete commented-out dead code left from old register-module codegen (#9707) by @hyf0
- deps: update napi-rs toolchain (#9706) by @shulaoda
- deps: update rollup submodule for tests to v4.61.1 (#9676) by @rolldown-guard[bot]
- deps: update test262 submodule for tests (#9677) by @rolldown-guard[bot]
- deps: update oxc to 0.135.0 (#9670) by @Boshen
- pass ALGOLIA_APP_ID and ALGOLIA_API_KEY to void deploy (#9667) by @Boshen
- deps: update github actions (#9662) by @renovate[bot]
- deps: update rust crates (#9663) by @renovate[bot]
- deps: update rolldown-plugin-dts to v0.25.2 (#9661) by @renovate[bot]
- deps: update typos to v1.47.2 (#9660) by @renovate[bot]
- deps: update docs dependencies (#9657) by @bddjr
- deps: update typos to v1.47.1 (#9655) by @renovate[bot]
- deploy website in its own workflow, only on docs output change (#9650) by @Boshen
- publish to pkg.pr.new add pm and `commentWithDev` option (#9638) by @btea

### ❤️ New Contributors

* @chuganzy made their first contribution in [#9654](#9654)
* @cjc0013 made their first contribution in [#9546](#9546)