Add CI check for missing workspace packages in Dockerfiles

Adds a script that verifies every packages/*/package.json is listed in
all app Dockerfiles. Catches the recurring issue where adding a new
workspace package breaks production because the Dockerfile deps stage
doesn't know about it.

Also fixes two pre-existing missing packages in the planner Dockerfile
(api, map-core) caught by the new check.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -38,6 +38,13 @@ jobs:
         run: pnpm audit --audit-level=high
         continue-on-error: true
 
+  dockerfile-check:
+    name: Dockerfile Package Check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - run: bash scripts/check-dockerfiles.sh
+
   typecheck:
     name: Typecheck
     runs-on: ubuntu-latest