## Summary

Adds three executable **flag-off** regression fixtures for wrapped-ESM init emission changes that landed with #10104. None enables `strictExecutionOrder`, and this PR changes no production source.

The earlier version of this PR required each barrel directly, which wrapped the immediate importee and bypassed the shared init-target collector it claimed to cover. The two collector fixtures now keep the immediate barrel at `WrapKind::None` in a shared chunk, while later `require()` calls wrap the leaf owners and make their init symbols reachable from the main chunk.

## Coverage

### Importer-local namespace liveness

`namespace_liveness_gating` imports the barrel namespace but reads only `ns.a()`. A second entry places the unwrapped barrel in a shared chunk; later requires make both wrapped leaf init symbols reachable.

- Current output emits only `init_leaf_a()` at the namespace-import position. `init_leaf_b()` stays at its later explicit require position.
- Pre-#10104 output emitted `init_leaf_a(), init_leaf_b()` together at the namespace-import position.
- The shared barrel still evaluates both leaves exactly once; runtime order is `A, B, BEFORE_REQUIRE:a, MAIN`.

### Sorted, non-ambiguous star-export routing

`ambiguous_star_reexport` has two wrapped leaves that both export `x`. The entry uses a real `export * from` record; a dynamic CommonJS re-export keeps that record included, while the second entry keeps the immediate barrel unwrapped and in another chunk.

- Current output excludes ambiguous `x` from the collector's sorted, non-ambiguous export map and emits no owner init before `__reExport(...)`.
- Pre-#10104 output selected an ambiguous owner and emitted `init_mod_a()` before `__reExport(...)`.
- Runtime confirms `x` is absent and both owners still evaluate exactly once through the shared barrel.

### Excluded re-export to a TLA wrapper

`excluded_reexport_tla` uses `codeSplitting: false`, so an inline dynamic import wraps the barrel and its static dependency chain even with strict execution order disabled. With `moduleSideEffects: false`, the carrier's unused re-export is excluded while the same TLA leaf remains live through a separate `used` import.

- Current output emits `await init_leaf()` in the carrier's async wrapper before its later statement.
- Pre-#10104 output emitted bare `init_leaf()`, producing `CARRIER:undefined` before the leaf's top-level await completed.
- Current runtime order is `LEAF:before, LEAF:after, CARRIER:ready, BARREL:used:marker`.

## Behavior / snapshot impact

Tests only: two existing fixtures are corrected, one TLA fixture is added, and their generated snapshots are pinned. No existing production code or unrelated snapshot changes.

## Validation

- Rebased onto `main` at `cccf1d0d849c71e80c02fe3ff17a97192f3bf258`.
- Generated all three fixtures with the macOS native binding from current-main CI [run 29795703407](https://github.com/rolldown/rolldown/actions/runs/29795703407); every `_test.mjs` passed under Node.
- Compared each committed snapshot byte-for-byte with those generated assets after applying the integration harness's runtime-module hiding.
- Re-ran the same sources with the pre-#10104 binding from CI [run 29559371389](https://github.com/rolldown/rolldown/actions/runs/29559371389): both collector fixtures show the obsolete extra init, and the TLA fixture logs `CARRIER:undefined`.
- `vp fmt ... --check`, `typos`, JS syntax checks, JSON parsing, and `git diff --check` pass. The pre-commit `vp check --fix` hook also completed cleanly.

- CI [run 29819995357](https://github.com/rolldown/rolldown/actions/runs/29819995357): Repo, Rust, Node, Cargo, WASI, native-build, and Node 20/22/24 test jobs passed. Vite Test Ubuntu and the three Ubuntu Dev Server jobs stopped before tests because the Vite `rolldown-canary` branch no longer rebases cleanly onto `vite/main` (`pnpm-lock.yaml` conflict); this is unrelated Vite checkout noise.

## AI usage disclosure

Per the [AI Usage Policy](https://rolldown.rs/contribution-guide/#ai-usage-policy), OpenAI Codex was used to rebase and review the PR, design the corrected regression shapes, and verify generated output. I reviewed the final diff and validation evidence.

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Follow-up to #10104; addresses Major 2b/2c from the review discussion: #10104 (comment)