Add ESLint and typecheck to CI, update docs

Replace the dummy CI workflow with one that runs ESLint and tsc on
every push and PR. Document how to run both checks via Docker.

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

Author: ambv

.github/workflows/ci.yml

@@ -1,11 +1,24 @@
-name: Dummy-CI
+name: CI
 
-on: [push]
+on:
+  push:
+    branches: [main]
+  pull_request:
 
 jobs:
-  build:
+  frontend-lint:
+    name: Frontend Lint & Typecheck
     runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: frontend
     steps:
-    - uses: actions/checkout@v1
-    - name: Pass
-      run: echo Success!
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+          cache-dependency-path: frontend/package-lock.json
+      - run: npm ci
+      - run: npm run lint
+      - run: npm run typecheck

README.md

@@ -42,10 +42,17 @@ make dev-backend     # Backend API on http://localhost:8000
 
 ### Testing
 ```bash
-npm run lint                # Frontend linting (in frontend directory)
+# Via Docker (recommended)
+docker compose -f docker-compose.dev.yml exec frontend npm run lint
+docker compose -f docker-compose.dev.yml exec frontend npm run typecheck
+
+# Or locally in the frontend directory
+npm run lint                # ESLint (must pass with zero errors)
 npm run typecheck           # TypeScript type checking
 ```
 
+Both checks run in CI on every push and pull request.
+
 ### Database Management
 ```bash
 make reset-db               # Drop and recreate database with fresh data

docker-README.md

@@ -130,6 +130,16 @@ ADMIN_GITHUB_TEAMS=memory-python-org
 
 **Note:** Development compose file uses port 9002 for frontend, production uses 3000.
 
+### Linting & Type Checking
+
+```bash
+# ESLint (must pass with zero errors)
+docker compose -f docker-compose.dev.yml exec frontend npm run lint
+
+# TypeScript type checking
+docker compose -f docker-compose.dev.yml exec frontend npm run typecheck
+```
+
 ### Accessing the Database
 
 ```bash