feat(v6): remove deprecated public API

[adrcotfas]

Motivation

• Delete src/deprecated.ts and all MD3*/DefaultTheme/useAppTheme re-exports
• Remove createMaterialBottomTabNavigator and entire src/react-navigation/ directory
• Remove theme.mode field from Theme type and DarkTheme definition
• Remove ThemeBase type
• Remove deprecated component props: FAB.small, Button.color, BottomNavigation BaseRoute.color
• Remove Card adaptive dark mode logic (tonal surfaces handle dark theme in MD3)
• Update example app and docs to use canonical names (Palette, LightTheme, DarkTheme)
• Rename internal useAppTheme to _useTheme to avoid confusion with removed public symbol

Related issue

See https://www.notion.so/callstack/React-Native-Paper-Foundation-for-MD3-Expressive-34c5d027c0f880edba3df107cd35946f?source=copy_link

Merge order:

• refactor: remove MD3 prefix and use deprecated aliases #4910
• refactor: move styles/ into src/theme/ tree #4915
• refactor: add color role table and buildScheme #4916
• feat: add theme.state opacity tokens and split theme types #4917
• feat: add theme.shapes and cornersToStyle #4919
• feat: add emphasized typescale and fix letter-spacing spec bugs #4920
• feat: add motion tokens (spring, easing, duration) #4922
• feat: add elevation tokens and fix Android dp spec bug #4923
• refactor(PaperProvider): add reduceMotion prop and useReduceMotion hook #4924
• feat: add dynamicColor prop and DynamicTheme refactor #4925
• refactor: replace string with ColorValue for ThemeColors #4945
• feat(v6): remove deprecated public API #4926
• docs: update documentation #4927

Test plan

• yarn typescript -- no new type errors
• yarn test -- all tests pass

[github-actions]

The mobile version of example app from this branch is ready! You can see it here.

[callstack-bot]

Hey @adrcotfas, thank you for your pull request 🤗. The documentation from this branch can be viewed here.