Windows CRT fix, cache hashing, and baseline checks

Fix Windows vendor sub-builds from leaking the dynamic CRT (9d51af8)

Bun now explicitly sets CMAKE_MSVC_RUNTIME_LIBRARY to static CRT mode and forwards that setting into nested CMake builds, preventing /MD from sneaking into vendored sub-builds. A new Windows PE import allowlist test makes CI fail if bun.exe ever starts importing VCRUNTIME140.dll or other non-system DLLs.

Prevent spawnSync from draining microtasks (7a498af)

The isolated event loop used by Bun.spawnSync now suppresses microtask drains so it can process subprocess I/O without accidentally running user JS from the shared JSC microtask queue. This closes a subtle cross-contamination bug that could have triggered callbacks at the wrong time.

Include --feature flags in transpiler cache hashing (91c7927)

Runtime transpiler cache keys now incorporate bundled feature flags, and the flags are sorted first so CLI order does not affect the hash. That prevents stale cached output when feature("...")-guarded code is compiled under different --feature settings.

Fix Windows numeric fs.open flags translation (5296e99)

Numeric open flags from fs.constants on Windows are now converted from MSVC/libuv values into Bun’s internal flag representation before reaching libuv. This fixes fs.openSync and fs.promises.open failures like EINVAL, and prevents flags such as O_CREAT from being silently dropped.

Add static baseline CPU instruction verifier (fbfd069)

Bun’s baseline verification pipeline now includes a static scanner that disassembles .text and flags instructions above the target ISA before emulator-based tests run. This catches -march leaks and other baseline violations earlier, making regressions much harder to miss.

Other misc changes

• Baseline WebKit artifact selection updated for baseline builds.
• CI baseline verification now uses the bun-profile artifact and builds the static scanner first.
• Minor internal refactors and test additions around the new baseline/static-check tooling.