Activate Bun.Transpiler REPL mode corpus

The current upstream js/bun/transpiler/repl-transform.test.ts fixture is still replaced with a synthetic TODO even though Home carries Bun parser REPL transforms. Activating it exposes three missing end-to-end semantics:

• the native transpiler bridge does not propagate replMode or disable DCE/object-literal ambiguity as Bun does
• Home Zig parser rewrites top-level REPL this to CommonJS exports, unlike current Bun
• the corpus node:vm shim does not persist top-level declarations on the context object

Acceptance criteria:

• execute the unmodified current Bun fixture instead of a TODO
• preserve top-level this in parser REPL mode
• support top-level await and object-literal disambiguation
• persist variables, functions, classes, and destructuring across vm context evaluations
• pass the exact fixture (36/36) and the complete home_test gate

This continues #66 and #81 after #90.

Completed and pushed to main in e2377b8 (feat(test): activate transpiler repl mode corpus).

What landed:

• activated the unmodified current Bun repl-transform.test.ts fixture
• propagated replMode into the persistent native transpiler handle and real parser flags
• disabled DCE and disambiguated leading object literals in REPL mode, matching Bun
• ported current Bun parser behavior that preserves top-level REPL this instead of rewriting it to CommonJS exports
• made node:vm context evaluation persist top-level declarations and use the context as the REPL receiver
• scoped the non-REPL await bar() diagnostic so top-level REPL await reaches the parser
• added a repository regression that executes the full upstream matrix

Verification:

• exact upstream fixture: 36 passed, 0 failed, 0 unsupported, 0 todo
• debug build: passed
• Zig formatting and diff checks: passed
• complete home_test gate: passed with zero failures

Commit author and committer are Chris chrisbreuer93@gmail.com; no coauthors.