Fix issues flagged by flutter analyze

This fixes code quality issues that flutter analyze catches and adds a CI step to Github Actions to flag on any future issues.

.github/workflows/flutter_analyze.yml

@@ -0,0 +1,23 @@
+name: Flutter Analyze
+
+on:
+  pull_request:
+  push:
+
+jobs:
+  analyze:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+
+      - name: Install dependencies
+        run: flutter pub get
+
+      - name: Analyze
+        run: flutter analyze --fatal-infos --fatal-warnings