Migrate to SvelteKit, Bun, Drizzle, and Tailwind v4

[google-labs-jules]

This PR migrates the legacy Next.js application to a modern stack using SvelteKit, Bun, Drizzle ORM, and Tailwind CSS v4.

Key Changes:

1. Framework: Migrated from Next.js to SvelteKit, leveraging Svelte 5's Runes syntax ($state, $props).
2. Runtime: Switched to Bun for faster installs and runtime execution, utilizing native APIs like Bun.password.
3. Database: Switched from Prisma/MySQL to Drizzle ORM with PostgreSQL support. Schema defined in src/lib/server/db/schema.ts with explicit types to avoid circular dependency issues.
4. API: Replaced tRPC with standard SvelteKit API routes (+server.ts).
5. Styling: Upgraded to Tailwind CSS v4 using the @tailwindcss/vite plugin, removing PostCSS dependencies.
6. Authentication: Implemented custom JWT-based authentication with Bun.password for hashing.

Verification:

• bun run check passes.
• bun run build passes (verified with dummy .env).
• Frontend verification confirmed via Playwright screenshot of the homepage.

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PR created automatically by Jules for task 16660516722151089045 started by @arisris

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