build: add a browser-test exclusion check and a pre-push static-check hook

npm run check:browser-excludes finds tests that import a browser driver and
asks `vitest list` whether the CI config still collects them; wired into CI.
npm install now also installs a marker-owned pre-push hook that runs the
static CI checks (~15s). Skip with CODEMAN_SKIP_PREPUSH=1; hand-written
hooks are left alone.

package.json

@@ -28,6 +28,7 @@
     "pretest:mobile": "node scripts/prepare-test-vendor.mjs",
     "test:mobile": "vitest run --config test/mobile/vitest.config.ts",
     "check:frontend-syntax": "node scripts/check-frontend-syntax.mjs",
+    "check:browser-excludes": "node scripts/check-browser-test-excludes.mjs",
     "fix:node-pty": "node scripts/fix-node-pty.mjs",
     "typecheck": "tsc --noEmit && tsc -p config/tsconfig.scripts.json",
     "lint": "eslint --config config/eslint.config.js 'src/**/*.ts'",