refactor: convert to bun workspaces monorepo

- Move web app into apps/web/
- Create packages/shared/ with shared types
- Create plugins/decky-vault/ scaffold
- Root package.json manages workspaces only

apps/web/lib/db/index.ts

@@ -0,0 +1,9 @@
+import { drizzle } from "drizzle-orm/node-postgres"
+import { Pool } from "pg"
+import * as schema from "./schema"
+
+const pool = new Pool({
+  connectionString: process.env.DATABASE_URL,
+})
+
+export const db = drizzle(pool, { schema })