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.

packages/split_button_m3e/pubspec.yaml

@@ -0,0 +1,22 @@
+name: split_button_m3e
+description: "Material 3 Expressive Split Button with sizes, variants, shapes, a11y, and menu."
+version: 0.1.0
+repository: https://github.com/EmilyMonestone/split_button_m3e
+issue_tracker: https://github.com/EmilyMonestone/split_button_m3e/issues
+
+environment:
+  sdk: ^3.9.2
+  flutter: ">=1.17.0"
+
+dependencies:
+  flutter:
+    sdk: flutter
+  m3e_design:
+    path: ../m3e_design
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+
+flutter:
+  uses-material-design: true