Port native bun:test module ABI and expect.assertions reporter

Tracks the bounded Bun compatibility slice exposed by js/bun/test/expect-assertions.test.ts.

Scope:

• align Home’s ResolvedSource builtin tags with the linked ~/Code/bun generated SyntheticModuleType ABI
• ensure bun:test resolves to the native Bun test module rather than the colliding node:test registry entry
• preserve the current Home executable for nested debug test runs
• propagate Bun.$.Shell() cwd/env/nothrow state into executed commands
• activate and pass the exact copied upstream expect-assertions.test.ts corpus file

Parent tracker: #66 Global gate tracker: #81

Completed in 496160c (fix(test): align native bun test module ABI).

Delivered:

• synchronized Home’s builtin ResolvedSource tags with the linked ~/Code/bun codegen ABI (Bun commit 4982b91e3702094330f3be3883354c52b8c01323)
• restored native bun:test resolution (expect present; mistaken node:test run export absent)
• preserved the active home-debug executable for nested test runs
• propagated Bun.$.Shell() cwd/env/nothrow state
• activated exact js/bun/test/expect-assertions.test.ts

Verification:

• exact upstream corpus file: 1 pass, 0 fail
• nested native fixture: expected 0 pass / 5 fail, exit 1
• collateral imports: node:test, node:fs, and node:buffer resolve correctly
• home_test gate: 1,059 pass, 1 skip, 1 pre-existing pipeline assertion fail across 1,061 tests

No coauthors; pushed directly to main as Chris.