build: drop Node from Docker, patch @volar/typescript for Bun

[kernoeb]

Summary

• Drops Node 24 from the build stage of Dockerfile (was only there for vue-tsc)
• Adds a bun patch on @volar/typescript@2.4.28 to fix the long-standing incompat where Bun's module loader does not honor fs.readFileSync monkey-patching — the trick Volar uses to inject .vue extension support into TypeScript (Bun issue 4754, opened 2023).
• The patch replaces the monkey-patch with a direct Module#_compile call, honored by both Node and Bun. Same fix lives on a fork at kernoeb/volar.js@fix-bun-vue-tsc.

What the patch does

Before	After
Monkey-patches fs.readFileSync to intercept Node's CJS loader read of tsc.js	Reads tsc.js directly, transforms it, then Module#_compiles the result
Uses a thrown transformTscContent failure as the "this is the v5.7+ shim" signal	Detects the shim with a regex up front; real transform failures now surface their real error
No BOM strip (relied on Node's Module._extensions['.js'] wrapper)	Explicitly strips UTF-8 BOM before compiling
No compile cache (the v5.7+ tsc shim called enableCompileCache(), our patch bypassed it)	Calls Module.enableCompileCache() to mirror the shim

Test plan

• docker build --target build passes end-to-end in ~44s (was building successfully with Node previously)
• bun install re-applies the patch automatically (verified on clean rm -rf node_modules && bun install)
• bun run typecheck (= vue-tsc -b --force) exits 0
• bun run test:unit — 136 tests, 5704 expect() calls, all green
• Production image runs and serves /api/ping as before (smoke-test on test server)

Notes

• @volar/typescript 2.4.28 is the version currently pinned via bun.lock. If volar bumps minor we'll need to regenerate the patch — bun patch will fail-loud on hash mismatch.
• The fork is not yet a PR upstream — we keep the local patch until Volar merges it.