[stuffbucket]

What

The Bun pin moves from 1.3.14 to 1.4.3. That covers .bun-version and every bun-version: in the workflows, as docs/bun-version-policy.md requires. The MCP broker already builds with 1.4.3 (packages/mcp-broker/mise.toml), so after this change one Bun builds everything.

Why now:

• Bun 1.4 rewrote node:http. The broker moved to 1.4 for that reason (see the policy doc).
• Bun 1.4 is the first release with bun:ffi on Windows ARM64. 1.3.14's ARM64 build has TinyCC disabled. A native ARM64 Windows build needs FFI for the MCP broker's Job Object containment.

Checked on 1.4.3

• bun test: 2349 pass, 0 fail. bun run check:fast, knip and bun run check:deep are clean.
• bun run app:sidecar builds the UI, the sidecar and the broker on macOS. The compiled sidecar starts, /status reports ok, and /ui/settings/, /ui/dashboard/ and /token-usage/sessions answer.
• The sidecar cross-compiles for windows-x64, windows-aarch64, linux-x64 and linux-arm64.
• In a Windows 11 ARM64 VM, the windows-x64 build (under emulation) and the windows-aarch64 build (native) each start, report ok on /status, and serve Settings.
• In the same VM, bun:ffi dlopen of kernel32 works on 1.4.3 for both arm64 and x64. On 1.3.14 arm64 it fails with "TinyCC is disabled".

Not checked

• The Tauri app run against a 1.4.3 sidecar (bun run app:dev). The next rc tests that on macOS and Windows.