feat: add theme provider and control components for light/dark mode

- Implemented ThemeProvider to manage theme state and preferences.
- Added ThemeControl component for users to switch between system, light, and dark themes.
- Integrated localStorage for theme preference persistence.
- Updated document styles based on theme changes.

test: add tests for permanent deletion of habits and related records

- Created tests to ensure permanent deletion of habits removes all dependent records.
- Verified that deletion requires ownership, authentication, and checks for archived habits.
- Added tests to confirm rollback behavior on deletion failures.

test: add tests for habit palette and progress card functionality

- Implemented tests for habit color progression and theme-based color shading.
- Added tests for progress card calculations and calendar display logic.

feat: define theme types and preferences

- Introduced Theme and ThemePreference types for better type safety.
- Created utility functions for resolving theme based on user preference and system settings.
- Defined theme palettes for light and dark modes to ensure adequate contrast.

scripts/share-card-preview.ts

@@ -0,0 +1,5 @@
+// Run with: bun scripts/share-card-preview.ts
+// Optional mobile iframe: SHARE_PREVIEW=1 bun scripts/dashboard-preview.ts
+import page from "./share-card-preview.html";
+const server = Bun.serve({ hostname: "127.0.0.1", port: 3108, routes: { "/*": page }, development: true });
+console.log(`Sharing visual fixtures: ${server.url}`);