chore: apply CI improvements and remove stale task artifacts (#12)

- Increase CUA smoke test timeout to 60min
- Add npm and Gradle caching to CI workflow
- Add emulator to PATH explicitly
- Remove .tasks/ directory (stale tracking files)

Closes #11

Co-authored-by: engineer <engineer@opencode.ai>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/workflows/cua-smoke.yml

@@ -13,13 +13,14 @@ on:
 jobs:
   cua-test:
     runs-on: ubuntu-latest
-    timeout-minutes: 30
+    timeout-minutes: 60
     steps:
       - uses: actions/checkout@v6
 
       - uses: actions/setup-node@v6
         with:
           node-version: 20
+          cache: npm
 
       - uses: actions/setup-java@v5
         with:
@@ -29,6 +30,20 @@ jobs:
       - name: Setup Android SDK
         uses: android-actions/setup-android@v4
 
+      - name: Add emulator to PATH
+        run: echo "$ANDROID_HOME/emulator" >> $GITHUB_PATH
+
+      - name: Cache Gradle
+        uses: actions/cache@v5
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+            android/.gradle
+          key: ${{ runner.os }}-gradle-${{ hashFiles('android/**/*.gradle*', 'android/gradle/wrapper/gradle-wrapper.properties') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+
       - name: Install Android system image & create AVD
         run: |
           sdkmanager "system-images;android-34;google_apis;x86_64" "emulator"