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.

.github/workflows/ci.yml

@@ -34,6 +34,13 @@ jobs:
       - name: Frontend JS syntax check
         run: npm run check:frontend-syntax
 
+      # Asks `vitest list` what CI would actually collect, rather than matching
+      # filenames: a browser-driven test missing from BROWSER_TEST_GLOBS
+      # (config/test-suites.ts) passes locally and dies in the test job with
+      # "browserType.launch: Executable doesn't exist".
+      - name: Browser-test exclusion check
+        run: npm run check:browser-excludes
+
       - name: Format check
         run: npm run format:check