feat(MattiUI): Upgrade to Material Design 3 with full Jetpack Compose-aligned component library

[Copilot]

MattiUI had a small set of rough M2-era components with no theming system. This PR introduces a complete Material Design 3 component library with an environment-based theme, using Jetpack Compose M3 naming conventions, plus a fully rewritten sample project showcasing all components via SwiftUI previews.

Theme System (Sources/MattiUI/Theme/)

• MaterialColorScheme — 30 M3 color roles, baseline light/dark purple palettes, public Color(m3hex:) extension
• MaterialTypography — full type scale (displayLarge → labelSmall) with font, line-height, and letter-spacing
• MaterialShapes — shape scale (extraSmall 4pt → full 50pt)
• MaterialTheme — environment-injected via .materialTheme() / @Environment(\.materialTheme)

MyApp()
    .materialTheme(.init(colorScheme: .light))

New Components (Jetpack Compose M3 naming)

Category	Components
Buttons	FilledButton, OutlinedButton, TextButton, ElevatedButton, FilledTonalButton
FAB	FloatingActionButton, SmallFloatingActionButton, LargeFloatingActionButton, ExtendedFloatingActionButton
Cards	ElevatedCard, FilledCard, OutlinedCard
Chips	AssistChip, FilterChip, InputChip, SuggestionChip
Text Fields	FilledTextField, OutlinedTextField (floating label, icons, error state)
Selection	MaterialSwitch (thumb icon + spring animation), MaterialCheckbox, MaterialRadioButton, MaterialRadioGroup
Progress	LinearProgressIndicator, CircularProgressIndicator (determinate + indeterminate)
Navigation	NavigationBar + NavigationBarItem (M3 active indicator pill)
App Bars	TopAppBar, CenterAlignedTopAppBar, MediumTopAppBar, LargeTopAppBar
Misc	AlertDialog, Badge, BadgedBox, MaterialDivider, Snackbar + .snackbar(data:onAction:) modifier

Sample Project

ContentView.swift replaced with a 4-tab showcase app (NavigationBar-driven: Buttons, Cards & Chips, Inputs, Misc) demonstrating every component with live PreviewProviders per section.

Backward Compatibility

All original components (MaterialButton, Card, MaterialToggle, MaterialDateTimePicker, Rating, ContainerWithFloatingButton) are untouched.

Original prompt

I need you to update this repository to use the latest material design from Google and provide examples in SwiftUI previews on a sample project so that we can see how they look and match it as close as you can to what material design has use similar naming conventions for the components of android jet pack compose

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.