Adds the `PackageImportMethod` variant to `LogEvent` and emits it from
`Install::run` after `pnpm:context`, before `pnpm:stage importing_started`.
Mirrors pnpm's emit at
https://github.com/pnpm/pnpm/blob/086c5e91e8/fs/indexed-pkg-importer/src/index.ts#L32.

The wire-format enum has only `clone | hardlink | copy`; pacquet's
`Npmrc::package_import_method` adds `Auto` and `CloneOrCopy`. Both
collapse to `clone` because that's the optimistic path the upstream
auto-importer attempts first. For the explicit `Hardlink` / `Copy` /
`Clone` settings the wire value matches reality. A TODO at the emit
site notes that the value should be re-derived after the first
successful import once the fallback signal is surfaced past the
per-package import path.

While auditing this channel, also deferred `pnpm:stage
resolution_started/done`: pacquet's no-lockfile flow interleaves
resolution and import per dependency, so emitting `resolution_done`
after import work has already happened would break the JS reporter's
per-package state. Pick this back up once pacquet's no-lockfile flow
gains a separate resolution pass. Frozen-lockfile installs (pacquet's
primary path today) don't need these events anyway — pnpm itself skips
them in `deps-restorer`. The deferral is recorded under #347.

Tests:
- New `package_import_method_event_matches_pnpm_wire_shape` in the
  reporter crate asserts every wire value renders correctly.
- The install integration test grows to assert the five-event success
  sequence (Context, PackageImportMethod, ImportingStarted,
  ImportingDone, Summary) and spot-checks the wire mapping for the
  default `Auto` config (collapses to `Clone`).
- Verified the test catches the regression by temporarily commenting
  out the new emit and confirming the failure shape, then restored.

Refs #347. Engine: #345. Previous channel: #355.

Adds the `PackageImportMethod` variant to `LogEvent` and emits it from
`Install::run` after `pnpm:context`, before `pnpm:stage importing_started`.
Mirrors pnpm's emit at
https://github.com/pnpm/pnpm/blob/086c5e91e8/fs/indexed-pkg-importer/src/index.ts#L32.

The wire-format enum has only `clone | hardlink | copy`; pacquet's
`Npmrc::package_import_method` adds `Auto` and `CloneOrCopy`. Both
collapse to `clone` because that's the optimistic path the upstream
auto-importer attempts first. For the explicit `Hardlink` / `Copy` /
`Clone` settings the wire value matches reality. A TODO at the emit
site notes that the value should be re-derived after the first
successful import once the fallback signal is surfaced past the
per-package import path.

While auditing this channel, also deferred `pnpm:stage
resolution_started/done`: pacquet's no-lockfile flow interleaves
resolution and import per dependency, so emitting `resolution_done`
after import work has already happened would break the JS reporter's
per-package state. Pick this back up once pacquet's no-lockfile flow
gains a separate resolution pass. Frozen-lockfile installs (pacquet's
primary path today) don't need these events anyway — pnpm itself skips
them in `deps-restorer`. The deferral is recorded under #347.

Tests:
- New `package_import_method_event_matches_pnpm_wire_shape` in the
  reporter crate asserts every wire value renders correctly.
- The install integration test grows to assert the five-event success
  sequence (Context, PackageImportMethod, ImportingStarted,
  ImportingDone, Summary) and spot-checks the wire mapping for the
  default `Auto` config (collapses to `Clone`).
- Verified the test catches the regression by temporarily commenting
  out the new emit and confirming the failure shape, then restored.

Refs #347. Engine: #345. Previous channel: #355.

Adds the `PackageImportMethod` variant to `LogEvent` and emits it from
`Install::run` after `pnpm:context`, before `pnpm:stage importing_started`.
Mirrors pnpm's emit at
https://github.com/pnpm/pnpm/blob/086c5e91e8/fs/indexed-pkg-importer/src/index.ts#L32.

The wire-format enum has only `clone | hardlink | copy`; pacquet's
`Npmrc::package_import_method` adds `Auto` and `CloneOrCopy`. Both
collapse to `clone` because that's the optimistic path the upstream
auto-importer attempts first. For the explicit `Hardlink` / `Copy` /
`Clone` settings the wire value matches reality. A TODO at the emit
site notes that the value should be re-derived after the first
successful import once the fallback signal is surfaced past the
per-package import path.

While auditing this channel, also deferred `pnpm:stage
resolution_started/done`: pacquet's no-lockfile flow interleaves
resolution and import per dependency, so emitting `resolution_done`
after import work has already happened would break the JS reporter's
per-package state. Pick this back up once pacquet's no-lockfile flow
gains a separate resolution pass. Frozen-lockfile installs (pacquet's
primary path today) don't need these events anyway — pnpm itself skips
them in `deps-restorer`. The deferral is recorded under #347.

Tests:
- New `package_import_method_event_matches_pnpm_wire_shape` in the
  reporter crate asserts every wire value renders correctly.
- The install integration test grows to assert the five-event success
  sequence (Context, PackageImportMethod, ImportingStarted,
  ImportingDone, Summary) and spot-checks the wire mapping for the
  default `Auto` config (collapses to `Clone`).
- Verified the test catches the regression by temporarily commenting
  out the new emit and confirming the failure shape, then restored.

Refs #347. Engine: #345. Previous channel: #355.

Closes #346.

Adds a "Reporter / log events" section to `CODE_STYLE_GUIDE.md`
covering the convention for porting reporter emissions:

- **Finding the upstream emit** — three call shapes to grep for in
  `pnpm/pnpm` (`globalLogger.<channel>.<level>(...)`,
  `logger.<level>({ name: 'pnpm:<channel>', ... })`, and direct
  `streamParser.write(...)` calls).
- **Channel mapping** — `crates/reporter/src/lib.rs`'s `LogEvent`
  enum is the canonical list, with each variant pinning
  `#[serde(rename = "pnpm:<channel>")]`. Includes the convention
  for adding a new channel (mirror the upstream TS shape
  field-for-field, add a wire-shape unit test).
- **Threading** — `<R: Reporter>` generic on every fn that emits,
  turbofish at the production entry point, install-scoped state
  via parameters where dedup matters (e.g. `link_file`'s
  `&AtomicU8`).
- **Where to put the emit** — match the upstream call site's
  position relative to side effects; cite the upstream permalink
  at a pinned SHA in the code comment.
- **Testing** — recording-fake DI per #339, a `static
  Mutex<Vec<LogEvent>>` per test, sequence assertion via
  `matches!`. Verify the test catches the regression.
- **What not to do** — don't reformat upstream messages, don't
  invent channels, don't change emit granularity in either
  direction.
- **Worked example** — `pnpm:summary` in `Install::run` (landed in
  #355): shows the upstream permalink, the pacquet emit, and the
  test that pins the sequence.

Adds a sixth bullet to `AGENTS.md`'s cardinal rule pointing at the
new section, so the "match pnpm" mandate explicitly covers log
emissions.

A style guide should let a porter read it linearly without
context-switching to GitHub. The four issue references (#345 for
the reporter origin, #347 for the channel-backfill audit, #339 for
the recording-fake pattern, #355 for the worked example's PR) were
project history, not convention — none of them carried information
the doc itself didn't already restate inline.

Replace each with the concrete fact the reader needs: the reporter
lives in `crates/reporter` (with its trait, enum, and sinks named
in place); to add a new channel, do X, Y, Z (instead of "the work
tracked under #347"); the recording-fake pattern is the unit-struct
+ static-mutex shape (described directly, no "from #339"); and the
worked example is just the code, no "added in #355".