Add lint workflow and lint-fix script

Copied from splatoon3.ink: lint on pushes to main and on pull requests,
failing on any warning, and npm run lint-fix to apply fixes locally.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

.github/workflows/lint.yml

@@ -0,0 +1,20 @@
+name: Lint
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main", "develop" ]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+    - uses: actions/setup-node@v4
+      with:
+        node-version: 22
+        cache: 'npm'
+    - run: npm ci
+    - run: npm run lint -- --max-warnings 0

package.json

@@ -24,7 +24,8 @@
     "worker:dev": "wrangler dev --local --var LOCAL_DEVELOPMENT:true --persist-to .wrangler/state",
     "worker:test": "vitest run --config vitest.worker.config.mjs",
     "worker:deploy:dry-run": "wrangler deploy --dry-run",
-    "worker:deploy": "wrangler deploy"
+    "worker:deploy": "wrangler deploy",
+    "lint-fix": "npm run lint -- --fix"
   },
   "dependencies": {
     "@atproto/api": "^0.20.42",