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/toolbar_m3e/README.md

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+# toolbar_m3e
+
+Material 3 **Expressive** toolbar for Flutter – a compact action bar that can host a title/subtitle, leading widget, inline actions, and an overflow menu. All styling is driven by `m3e_design` tokens.
+
+- `ToolbarM3E` — the main toolbar widget (`PreferredSizeWidget`) for use in `Scaffold` or as a standalone header
+- `ToolbarActionM3E` — action model consumed by the toolbar
+- Inline actions render as icon buttons; extra actions go into a `PopupMenuButton` overflow
+
+## Monorepo Layout
+
+```
+packages/
+  m3e_design/
+  toolbar_m3e/
+```
+
+`pubspec.yaml` references `../m3e_design`.
+
+## Usage
+
+```dart
+import 'package:toolbar_m3e/toolbar_m3e.dart';
+
+final actions = [
+  ToolbarActionM3E(
+    icon: Icons.search,
+    onPressed: () {},
+    tooltip: 'Search',
+  ),
+  ToolbarActionM3E(
+    icon: Icons.share_outlined,
+    onPressed: () {},
+    tooltip: 'Share',
+  ),
+  ToolbarActionM3E(
+    icon: Icons.delete_outline,
+    onPressed: () {},
+    tooltip: 'Delete',
+    isDestructive: true,
+    label: 'Delete', // used in overflow
+  ),
+];
+
+ToolbarM3E(
+  leading: const BackButton(),
+  titleText: 'Selection',
+  subtitleText: '3 items',
+  actions: actions,
+  maxInlineActions: 2, // remaining actions go to overflow
+  variant: ToolbarM3EVariant.tonal, // surface | tonal | primary
+  size: ToolbarM3ESize.medium,      // small | medium | large
+  density: ToolbarM3EDensity.regular,
+  shapeFamily: ToolbarM3EShapeFamily.round,
+  centerTitle: false,
+);
+```
+
+## Tokens mapping
+
+- **Container**: `surfaceContainerHigh` (surface) / `secondaryContainer` (tonal) / `primaryContainer` (primary)
+- **Foreground**: `onSurface` / `onSecondaryContainer` / `onPrimaryContainer`
+- **Shape**: uses M3E `round` / `square` set (`md` radius)
+- **Heights**: small **≈40dp**, medium **≈48dp**, large **≈56dp**
+- **Icon size**: **24dp**
+- **Padding**: horizontal from tokens (`spacing.md`)
+
+## Overflow
+
+Set `maxInlineActions` to the number of actions that should stay inline. Any additional actions go to the overflow menu (labels pulled from `label` or `tooltip`/`semanticLabel`). Destructive actions can be highlighted by `isDestructive: true`.
+
+## Accessibility
+
+- Provide `semanticLabel` on the toolbar if useful.
+- Actions expose `tooltip` and can set `semanticLabel` to improve assistive tech hints.
+
+## License
+
+MIT