feat: add SvelteKit adapter

Add framework adapter for SvelteKit with:
- `getApp()` - get bknd app instance
- `serve()` - request handler for hooks.server.ts

Usage in hooks.server.ts:
```typescript
import { serve } from "bknd/adapter/sveltekit";
import config from "../bknd.config";

const bkndHandler = serve(config);

export const handle = async ({ event, resolve }) => {
  if (event.url.pathname.startsWith("/api/")) {
    return bkndHandler(event);
  }
  return resolve(event);
};
```

Includes:
- Adapter implementation (app/src/adapter/sveltekit/)
- Test suite
- Working example (examples/sveltekit/)
- Package exports and types

app/src/adapter/sveltekit/sveltekit.adapter.spec.ts

@@ -0,0 +1,15 @@
+import { afterAll, beforeAll, describe } from "bun:test";
+import * as sveltekit from "./sveltekit.adapter";
+import { disableConsoleLog, enableConsoleLog } from "core/utils";
+import { adapterTestSuite } from "adapter/adapter-test-suite";
+import { bunTestRunner } from "adapter/bun/test";
+
+beforeAll(disableConsoleLog);
+afterAll(enableConsoleLog);
+
+describe("sveltekit adapter", () => {
+   adapterTestSuite(bunTestRunner, {
+      makeApp: sveltekit.getApp,
+      makeHandler: (c, a) => (request: Request) => sveltekit.serve(c, a)({ request }),
+   });
+});