feat: add Home page with user dashboard and habit tracking features

- Implemented Home component with user authentication and loading states.
- Created Welcome component for unauthenticated users with a sign-in option.
- Developed Dashboard component to display user's habits and progress.
- Added functionality for habit management, including adding, updating, and deleting habits.
- Integrated HabitChart and HabitHistory components for visual representation of habits.
- Introduced sharing functionality for progress via Discord integration.

feat: establish Discord sharing configuration and routes

- Added DiscordSharingConfig type and readDiscordSharingConfig function for environment variable management.
- Created sharing contracts for input validation and data structure.
- Implemented sharing routes for previewing and sending progress images to Discord.
- Added tests for sharing routes to ensure authentication and proper error handling.

src/habits/service.ts

@@ -6,7 +6,7 @@ import { addDays, endOfDay, localDate, scheduled, schedulesOverlap, shade } from
 import { calendarSettingsSchema, habitInput, type HabitConfig, type CalendarSettings } from './contracts';
 
 export class ApiError extends Error {
-  constructor(public status: 400 | 404 | 409 | 422, message: string) { super(message); }
+  constructor(public status: 400 | 404 | 409 | 422 | 429 | 502, message: string) { super(message); }
 }
 const missing = () => new ApiError(404, 'Not found');
 export type Habit = typeof habits.$inferSelect;