- Replace custom Observable protocol and @Published with Apple's @Observable macro
- Add withObservationTracking in renderToBuffer for automatic per-property dependency tracking
- Add type-based @Environment(Type.self) and .environment(object) for observable objects
- Add ObjectEnvironmentModifier for injecting observable objects into the environment
- Add needsCacheClear flag to AppState for thread-safe cache invalidation
- Add cross-platform test script (scripts/test-linux.sh) for Docker-based Linux verification
- Add DemoAppHeader with system info display (OS, version, architecture)
- Consolidate Example App: extract ImageDemoHelpers, KeyboardHelpSection, ValueDisplayRow
- Add pre-push verification rule to CLAUDE.md
- Verified on both macOS and Linux (swift:6.0 container), 1155 tests passing
- Redesign Button rendering with half-block caps (U+2590/U+258C) and accent-tinted background
- Apply matching cap style and background to TextField and SecureField
- Add foregroundQuaternary to Palette for subtle UI elements like spinner tracks
- Fix border saturation in all palette presets to preserve hue instead of going gray
- Rework Spinner bouncing trail to interpolate from highlight to quaternary via Color.lerp
- Fix Spinner label to use palette foreground color
- Fix FrameDiffWriter to use ESC[2K for reliable line clearing
- Add Layoutable conformance to NavigationSplitView for height-flexible layout
- Update tests for new button cap style
phranck