1. Analyze the current Flutter theme state and identify legacy components.
2. Determine the Material 3 replacements for legacy widgets.
3. Implement the app-wide Material 3 theme using `ColorScheme.fromSeed`.
4. Normalize component themes by updating theme definitions in `ThemeData`.
5. Migrate legacy buttons and button styles using `styleFrom()` or `ButtonStyle`.
6. Apply platform-specific adaptations based on the host OS.
7. Validate the generated code and fix any remaining legacy components or properties.