feat: add database url

.env.example

···
 RP_ID=indiko.dunkirk.sh
 PORT=3000
 NODE_ENV="production"
+DATABASE_URL=data/indiko.db

src/db.ts

···
 
 Bun.write("data/.gitkeep", "");
 
-const db = new Database("data/indiko.db");
+const dbPath = process.env.DATABASE_URL || "data/indiko.db";
+const db = new Database(dbPath);
 
 db.run("PRAGMA journal_mode = WAL;");
 db.run("PRAGMA foreign_keys = ON;");