fix: lazy DB initialization — useDb() called inside handlers, not at import

useRuntimeConfig() and better-sqlite3 were being called at module
top-level, which crashes during Nitro server startup. Now all DB
access is lazy via useDb(), and auth uses process.env directly.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/api/ideas/[id].delete.ts

@@ -1,8 +1,9 @@
-import db from '../../utils/db'
+import { useDb } from '../../utils/db'
 import { requireAdmin } from '../../utils/auth'
 
 export default defineEventHandler((event) => {
   requireAdmin(event)
+  const db = useDb()
   const id = getRouterParam(event, 'id')
   db.prepare('DELETE FROM ideas WHERE id = ?').run(id)
   return { ok: true }