Add CI workflow and fix Flutter setup for CodeQL

Run analyze and tests on pushes and pull requests, and update the
CodeQL workflow so Flutter setup works reliably on GitHub Actions.

Author: r0073rr0r

.github/workflows/ci.yml

@@ -0,0 +1,37 @@
+name: Flutter CI
+
+on:
+  push:
+    branches:
+      - '**'
+  pull_request:
+
+jobs:
+  test:
+    name: Analyze and Test
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '17'
+
+      - name: Setup Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+          cache: true
+
+      - name: Install dependencies
+        run: flutter pub get
+
+      - name: Analyze
+        run: flutter analyze
+
+      - name: Run tests
+        run: flutter test

.github/workflows/codeql.yml

@@ -27,21 +27,25 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
+      - name: Set up Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '17'
+
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v3
         with:
           languages: ${{ matrix.language }}
 
-      # Install Flutter
       - name: Setup Flutter
         uses: subosito/flutter-action@v2
         with:
-          flutter-version: 'stable'
+          channel: stable
 
       - name: Install dependencies
         run: flutter pub get
 
-      # Manual build (ovo rešava CodeQL problem)
       - name: Build Android
         run: flutter build apk --debug