Use Node.js native sqlite instead of turso/libsql

Replaces @libsql/client with Node.js's built-in node:sqlite module.

Changes:
- Replace libsql/turso client with DatabaseSync from node:sqlite
- Remove @libsql/client dependency from package.json
- Remove --external:@libsql/client from bundler config
- Add NODE_NO_WARNINGS=1 to suppress experimental sqlite warnings
- Add explicit directory creation (was built-in with better-sqlite3)
- Use db.exec() for PRAGMA statements (db.pragma() doesn't exist)
- Wrap all operations in Promise.resolve() for FFI compatibility

Benefits:
- Zero external dependencies for SQLite
- Simpler implementation (no remote database support needed)
- Nearly identical API to the original better-sqlite3 version

All tests pass (235/239, same as baseline - 4 pre-existing failures
unrelated to SQLite changes).

Author: i-am-the-slime

bin/index.dev.js

@@ -1,5 +1,8 @@
 #!/usr/bin/env node
 
+// Suppress Node.js experimental warnings (specifically for SQLite)
+process.env.NODE_NO_WARNINGS = "1";
+
 import { main } from "../output/Main/index.js";
 
 main();

bin/spago.yaml

@@ -31,5 +31,3 @@ package:
     minify: false
     platform: node
     type: app
-    extraArgs:
-      - "--external:@libsql/client"