Add initial configuration, tokens, and widgets for M3E components

- Introduced `.gitignore` and `.metadata` for apps and examples.
- Added Flutter/Dart analysis configurations (`analysis_options.yaml`).
- Implemented foundational tokens and themes for M3E (colors, shapes).
- Created base implementations for `IconButtonM3E` and `SplitButtonM3E`.
- Set up CI workflow (`ci.yaml`) to automate testing and analysis.

.github/workflows/ci.yaml

@@ -0,0 +1,23 @@
+name: CI
+on:
+  push:
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+      - name: Install Melos
+        run: dart pub global activate melos
+      - name: Bootstrap
+        run: melos bootstrap
+      - name: Format
+        run: melos run format
+      - name: Analyze
+        run: melos run analyze
+      - name: Test
+        run: melos run test