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/icon_button_m3e/test/icon_button_m3e_test.dart

@@ -0,0 +1,46 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:icon_button_m3e/icon_button_m3e.dart';
+
+void main() {
+  testWidgets('Semantics exposes label and selected state', (tester) async {
+    const label = 'Favorite';
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Material(
+          child: IconButtonM3E(
+            icon: Icon(Icons.favorite_border),
+            selectedIcon: Icon(Icons.favorite),
+            isSelected: true,
+            tooltip: label,
+          ),
+        ),
+      ),
+    );
+
+    final semantics = tester.getSemantics(find.byType(IconButtonM3E));
+    expect(semantics.flagsCollection.hasSelectedState, true);
+    expect(semantics.label, label);
+  });
+
+  testWidgets('Hit target is at least 48x48 when visual is XS (32)', (
+    tester,
+  ) async {
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Material(
+          child: Center(
+            child: IconButtonM3E(
+              size: IconButtonM3ESize.xs,
+              icon: Icon(Icons.mic),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    final size = tester.getSize(find.byType(IconButtonM3E));
+    expect(size.width, greaterThanOrEqualTo(48));
+    expect(size.height, greaterThanOrEqualTo(48));
+  });
+}