Native bun:test: remove test.failing reporter suppressions

Scope

Remove Home's injected TODO/skip suppression for the unchanged Bun test.failing nested-runner suite, promote it through the production native test runner, and delete the stale async-iterator IPC suppression helper.

Parent parity tracker: #66 Suppression ledger: #202

Before

The routed Home corpus rewrote four test.failing groups into TODO/skip registrations:

• expected failing subprocesses that throw or reject;
• unexpected passing subprocess reporter output;
• timeout reporting;
• done-callback pass/fail reporting.

That produced 3 pass / 8 Home-injected TODOs even though the unchanged source already passed strictly through the production VM.

The async-iterator helper likewise encoded an IPC/header-continuation TODO, but its file had already moved to an unchanged native path, leaving the suppression helper dead.

Acceptance criteria

• Delete both suppression helpers.
• Route js/bun/test/test-failing.test.ts through the production native test runner.
• Keep source bytes identical to pinned Bun.
• Preserve all upstream assertions, subprocesses, timeout behavior, snapshots, and done callbacks.
• Ratchet the native corpus inventory.
• Pass Debug and ReleaseSafe with zero Home-injected TODOs.

Evidence

Source SHA-256 matches pinned Bun:

• async iterator: 47d1b32187fd77a0438eb7c8aa2ff2875d7bd180059b8d680a920f5e9b2e9dd5
• test.failing: 7ac035a83127cd9f0a8f7e0589a8d1501aafd48847404445f719413d4bf69b70

Pinned Bun 4982b91e3702094330f3be3883354c52b8c01323:

• async iterator: 86 pass / 0 fail
• test.failing: 8 pass / 0 fail

Home strict native before routing:

• async iterator: 86 pass / 0 fail
• test.failing: 8 pass / 0 fail

Home routed before:

• test.failing: 3 pass / 8 injected TODO / 0 fail

Home routed after, in both Debug and ReleaseSafe:

• async iterator: 86 pass / 0 fail / 0 TODO / 0 unsupported
• test.failing: 8 pass / 0 fail / 0 TODO / 0 unsupported

Closed by 2d212a7d8.

What landed:

• Deleted rewriteTestFailingCorpus, removing all four Home-injected TODO/skip groups for nested subprocess pass, failure, timeout, and done-callback reporting.
• Routed the unchanged js/bun/test/test-failing.test.ts through the production native test runner.
• Deleted the stale rewriteAsyncIteratorStreamCorpus helper; the unchanged async generator IPC/header-continuation case is already native and green.
• Added an exact positive/negative routing predicate test.
• Ratcheted the native corpus inventory from 279 to 280 files.

Evidence:

• Both copied sources are byte-for-byte identical to pinned Bun.
• Before: routed test-failing.test.ts reported 3 pass / 8 Home-injected TODO / 0 fail.
• Debug after: async iterator 86/86; test.failing 8/8; 0 fail / 0 TODO / 0 unsupported.
• ReleaseSafe after: async iterator 86/86; test.failing 8/8; 0 fail / 0 TODO / 0 unsupported.
• Pinned Bun 4982b91e3702094330f3be3883354c52b8c01323: the same 86/86 and 8/8 totals.
• Debug and ReleaseSafe builds passed for the exact corpus diff.
• Zig formatting and diff checks passed.

No fixture, assertion, timeout, subprocess workload, snapshot, or done-callback behavior was changed.