chore(bench): add parse-phase benchmark

.github/workflows/build.yml

@@ -40,6 +40,12 @@ jobs:
         if: matrix.node-version == '22'
         run: node scripts/bench-source-map.mjs --smoke
 
+      # Splits base Markdown parsing, source-map recording, and post-parse
+      # indexing. The smoke checks AST parity and 4x input growth only.
+      - name: Run parse-phase benchmark smoke
+        if: matrix.node-version == '22'
+        run: node scripts/bench-parse.mjs --smoke
+
   Lint:
     runs-on: ubuntu-latest
     strategy:

package.json

@@ -49,6 +49,7 @@
     "test:package": "publint && node scripts/test-package.mjs",
     "prebench:source-map": "pnpm run build",
     "bench:source-map": "node scripts/bench-source-map.mjs",
+    "bench:parse": "node scripts/bench-parse.mjs",
     "preprofile:source-map": "pnpm run build",
     "profile:source-map": "node --expose-gc scripts/profile-source-map-heap.mjs",
     "test:update": "jest --updateSnapshot",