ci: add lint and typecheck workflow

Run biome and tsc on every push and PR against main so
regressions are caught before merge. Enables the required-
status-check rule on branch protection.

Author: Aqib-Rime

.github/workflows/ci.yml

@@ -0,0 +1,43 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check:
+    name: Lint + typecheck
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Bun
+        uses: oven-sh/setup-bun@v2
+        with:
+          bun-version: 1.3.5
+
+      - name: Cache Turbo
+        uses: actions/cache@v4
+        with:
+          path: .turbo
+          key: ${{ runner.os }}-turbo-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-turbo-
+
+      - name: Install dependencies
+        run: bun install --frozen-lockfile
+
+      - name: Lint
+        run: bun run lint
+
+      - name: Typecheck
+        run: bun run typecheck