ci: parallelize jobs and add turbo cache persistence

Split single CI job into parallel lint + build-and-typecheck jobs.
Add turbo cache via actions/cache for faster subsequent runs.
Use single turbo invocation for build+typecheck to optimize task
scheduling. Add concurrency group to cancel stale PR runs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -6,10 +6,13 @@ on:
   pull_request:
     branches: [main]
 
-jobs:
-  ci:
-    runs-on: ubuntu-latest
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
 
+jobs:
+  lint:
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -27,12 +30,34 @@ jobs:
         run: pnpm install
 
       - name: Lint
-        run: |
-          pnpm --filter @multica/web lint
-          pnpm --filter @multica/desktop lint
+        run: pnpm turbo lint
 
-      - name: Type check
-        run: pnpm typecheck
+  build-and-typecheck:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
 
-      - name: Build
-        run: pnpm build
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Restore Turbo cache
+        uses: actions/cache@v4
+        with:
+          path: .turbo
+          key: turbo-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}-${{ github.sha }}
+          restore-keys: |
+            turbo-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}-
+            turbo-${{ runner.os }}-
+
+      - name: Build and type check
+        run: pnpm turbo build typecheck