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/m3e_design/lib/tokens/motion_tokens.dart

@@ -0,0 +1,43 @@
+import 'package:flutter/material.dart';
+
+@immutable
+class M3EMotion {
+  final SpringDescription spatialFast;
+  final SpringDescription spatialMedium;
+  final SpringDescription spatialGentle;
+
+  final SpringDescription effectsFast;
+  final SpringDescription effectsMedium;
+
+  final Duration fast;
+  final Duration medium;
+  final Duration slow;
+
+  const M3EMotion({
+    required this.spatialFast,
+    required this.spatialMedium,
+    required this.spatialGentle,
+    required this.effectsFast,
+    required this.effectsMedium,
+    required this.fast,
+    required this.medium,
+    required this.slow,
+  });
+
+  const M3EMotion.expressive()
+      : spatialFast = const SpringDescription(mass: 1, stiffness: 500, damping: 30),
+        spatialMedium = const SpringDescription(mass: 1, stiffness: 350, damping: 28),
+        spatialGentle = const SpringDescription(mass: 1, stiffness: 220, damping: 24),
+        effectsFast = const SpringDescription(mass: 1, stiffness: 420, damping: 32),
+        effectsMedium = const SpringDescription(mass: 1, stiffness: 280, damping: 28),
+        fast = const Duration(milliseconds: 150),
+        medium = const Duration(milliseconds: 250),
+        slow = const Duration(milliseconds: 400);
+
+  static M3EMotion lerp(M3EMotion a, M3EMotion b, double t) => a;
+}
+
+class SpringDescription {
+  final double mass, stiffness, damping;
+  const SpringDescription({required this.mass, required this.stiffness, required this.damping});
+}