…op-level bin re-link (#342) (pnpm#523)

Two related bin-linking behaviors deferred from #333.

Behavior 1 — hoisted-bin precedence:
- Add `BinOrigin { Direct, Hoisted }` discriminator to `PackageBinSource`.
- New top tier in `pick_winner`: Direct wins outright over Hoisted
  regardless of ownership / lexical order. Mirrors upstream's
  `preferDirectCmds` partition at
  https://github.com/pnpm/pnpm/blob/4750fd370c/bins/linker/src/index.ts#L92.
- New `link_top_level_bins(modules_dir, direct, hoisted)` helper in
  `pacquet-package-manager` mixes both candidate lists into one
  `link_bins_of_packages` call so the new tier resolves conflicts in
  a single pass — previously the two passes (SymlinkDirectDependencies
  for direct + hoist pass for publicly-hoisted) wrote shims
  independently and a hoisted bin could shadow a direct one when its
  package name was lexically smaller.

Behavior 2 — lifecycle-script-created bins:
- Add a post-`BuildModules` per-importer top-level bin link pass.
  Re-reading each direct dep's `package.json` after lifecycle
  scripts run picks up bins generated by `postinstall` (the
  `@pnpm.e2e/generated-bins` upstream fixture). Idempotent for
  unchanged shims via `is_shim_pointing_at`.
- Mirrors upstream's `linkBinsOfImporter` pass that runs after
  `buildModules` at
  https://github.com/pnpm/pnpm/blob/4750fd370c/installing/deps-installer/src/install/index.ts#L1539.

Supporting changes:
- `PackageBinSource::new(location, manifest)` constructor + `with_origin`
  builder so existing call sites don't have to spell out the new field.
- Public `direct_dep_names_for_importer` helper extracted from
  `SymlinkDirectDependencies` so the post-build pass uses the same
  filter (skipped / first-wins / link_only) as the symlink phase.
- `InstallFrozenLockfileError::TopLevelBinLink` for the new failure
  surface.

Tests:
- `direct_origin_wins_over_hoisted_regardless_of_lexical` — pins the
  new tier overrides lexical ordering.
- `hoisted_origin_loses_to_existing_direct` — pins both arms of the
  new tier (Direct incumbent vs Hoisted candidate).

…op-level bin re-link (pnpm#342) (pnpm#523)

Two related bin-linking behaviors deferred from pnpm#333.

Behavior 1 — hoisted-bin precedence:
- Add `BinOrigin { Direct, Hoisted }` discriminator to `PackageBinSource`.
- New top tier in `pick_winner`: Direct wins outright over Hoisted
  regardless of ownership / lexical order. Mirrors upstream's
  `preferDirectCmds` partition at
  https://github.com/pnpm/pnpm/blob/4750fd370c/bins/linker/src/index.ts#L92.
- New `link_top_level_bins(modules_dir, direct, hoisted)` helper in
  `pacquet-package-manager` mixes both candidate lists into one
  `link_bins_of_packages` call so the new tier resolves conflicts in
  a single pass — previously the two passes (SymlinkDirectDependencies
  for direct + hoist pass for publicly-hoisted) wrote shims
  independently and a hoisted bin could shadow a direct one when its
  package name was lexically smaller.

Behavior 2 — lifecycle-script-created bins:
- Add a post-`BuildModules` per-importer top-level bin link pass.
  Re-reading each direct dep's `package.json` after lifecycle
  scripts run picks up bins generated by `postinstall` (the
  `@pnpm.e2e/generated-bins` upstream fixture). Idempotent for
  unchanged shims via `is_shim_pointing_at`.
- Mirrors upstream's `linkBinsOfImporter` pass that runs after
  `buildModules` at
  https://github.com/pnpm/pnpm/blob/4750fd370c/installing/deps-installer/src/install/index.ts#L1539.

Supporting changes:
- `PackageBinSource::new(location, manifest)` constructor + `with_origin`
  builder so existing call sites don't have to spell out the new field.
- Public `direct_dep_names_for_importer` helper extracted from
  `SymlinkDirectDependencies` so the post-build pass uses the same
  filter (skipped / first-wins / link_only) as the symlink phase.
- `InstallFrozenLockfileError::TopLevelBinLink` for the new failure
  surface.

Tests:
- `direct_origin_wins_over_hoisted_regardless_of_lexical` — pins the
  new tier overrides lexical ordering.
- `hoisted_origin_loses_to_existing_direct` — pins both arms of the
  new tier (Direct incumbent vs Hoisted candidate).