Initial commit — AI-powered coding tutor (Professor)

Next.js 16, React 19, Monaco editor, Anthropic SDK, multi-provider AI,
Wandbox Python execution, iframe HTML preview, SQLite auth + session persistence.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

db/index.ts

@@ -0,0 +1,18 @@
+import Database from 'better-sqlite3';
+import { drizzle } from 'drizzle-orm/better-sqlite3';
+import * as schema from './schema';
+
+type DrizzleDb = ReturnType<typeof drizzle<typeof schema>>;
+const globalForDb = globalThis as unknown as { _professorDb?: DrizzleDb };
+
+function createDb(): DrizzleDb {
+  const sqlite = new Database('professor.db');
+  sqlite.pragma('journal_mode = WAL');
+  return drizzle(sqlite, { schema });
+}
+
+export const db: DrizzleDb = globalForDb._professorDb ?? createDb();
+
+if (process.env.NODE_ENV !== 'production') {
+  globalForDb._professorDb = db;
+}