feat: POSIX conformance test suite and implementation fixes (99.4%)

[NathanFlurry]

Summary

• Integrates the os-test POSIX.1-2024 conformance suite into WasmVM
• Builds all os-test programs to both wasm32-wasip1 and native x86_64
• Adds a Vitest-based conformance test runner with native parity comparison
• Fixes 23 implementation gaps across libc, kernel, VFS, and device layer
• Achieves 99.4% conformance (3330/3350 tests passing)

What changed

Infrastructure (US-001 → US-011)

• make fetch-os-test / make os-test / make os-test-native build targets
• posix-exclusions.json schema with honest categorization (wasm-limitation / wasi-gap / implementation-gap)
• posix-conformance.test.ts test runner with native parity detection
• validate-posix-exclusions.ts validation script
• generate-posix-report.ts MDX report generator
• import-os-test.ts upstream update script
• .github/workflows/posix-conformance.yml CI workflow

Kernel & runtime fixes (US-012 → US-034)

• stdout duplication — removed redundant callback wiring in spawnManaged()
• VFS directory enumeration — fdOpen detects directories by stat; VFS populated from native build
• VFS stat metadata — fstatat parent-relative path lookup
• fcntl F_GETFD/F_SETFD — sysroot override tracks per-fd cloexec state
• realloc(ptr, 0) — sysroot patch enables REALLOC_ZERO_BYTES_FREES in dlmalloc
• namespace tests — stub main() for compile-only header conformance checks
• POSIX directory hierarchy — kernel creates /tmp, /usr, /etc, /var, etc. at startup
• glob/globfree — fixed by VFS directory enumeration fix
• strfmon/strfmon_l — sysroot override for POSIX locale
• open_wmemstream — sysroot override tracks wchar_t count
• swprintf — sysroot override sets errno=EOVERFLOW
• inet_ntop — sysroot override for RFC 5952 IPv6 formatting
• pthread_condattr_getclock — sysroot patch fixes C operator precedence bug
• pthread_mutex_trylock/timedlock/settype — sysroot override fixes lock tracking
• pthread_attr_getguardsize/mutexattr_setrobust — sysroot override stores values
• pthread_key_delete — sysroot override fixes NULL thread-list dereference
• /dev/ptmx, /dev/random, /dev/tty, /dev/console, /dev/full — added to device layer
• long-double printf/scanf — linked -lc-printscan-long-double
• dev-ptc/dev-ptm — native parity detection (Sortix-specific paths)

Integrity fixes (US-023 → US-025, US-028, US-033)

• All 5 C override fixes moved from test-only to patched sysroot
• ffsll source replacement reverted — properly excluded as wasm-limitation
• 7 pthread exclusions recategorized from wasm-limitation to implementation-gap
• Suite-specific VFS special-casing removed

Remaining exclusions (20 tests)

Category	Count	Notes
implementation-gap	17	stdio/wchar pipe I/O, poll/select pipe FDs, fmtmsg
wasi-gap	2	statvfs/fstatvfs (not in WASI spec)
wasm-limitation	1	ffsll (32-bit long truncates 64-bit constant)

Test plan

• make -C native/wasmvm/c os-test os-test-native compiles all tests
• pnpm vitest run packages/wasmvm/test/posix-conformance.test.ts passes
• pnpm tsx scripts/validate-posix-exclusions.ts passes
• No regressions in existing test suites
• Typecheck passes

🤖 Generated with Claude Code

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