build: restore +x on dist/src/main.js after tsc rebuild (#1644)

clean-dist deletes dist/ and tsc --build re-emits files without preserving
the executable bit on the bin entry. Symlinked global install then hits
EACCES on spawn until manually chmod'd. Chain a chmodSync into the existing
prebuild-manifest hook so any future rebuild self-heals.

node -e instead of bare `chmod +x` to keep the script portable (npm runs
on Windows via Git Bash where chmod is a no-op, but fs.chmodSync still
silently no-ops there too — no extra branching needed).

Co-authored-by: Kary <karyhe1019@gmail.com>

Author: huanghe

package.json

@@ -42,7 +42,7 @@
     "dev": "tsx src/main.ts",
     "dev:bun": "bun src/main.ts",
     "build": "npm run clean-dist && npm run copy-yaml && npm run build-manifest",
-    "prebuild-manifest": "tsc --build",
+    "prebuild-manifest": "tsc --build && node -e \"require('fs').chmodSync('dist/src/main.js', 0o755)\"",
     "build-manifest": "tsx src/build-manifest.ts",
     "clean-dist": "node scripts/clean-dist.cjs",
     "copy-yaml": "node scripts/copy-yaml.cjs",