feat: align SDK with updated OpenAPI spec and add missing unit tests

- Update generated types from new openapi.yaml (capsule stats, usage,
  metrics, pause/resume lifecycle, host/channel management, auth flow)
- Add Capsule pause/resume/ping/getMetrics lifecycle methods
- Add Capsule.waitForReady abort signal support
- Add PtyManager.connect and PtySession disposal
- Fix HttpClient empty-body response handling (content-length: 0)
- Add streamProcess() to CommandManager for background process streams
- Add integration tests for capsule lifecycle, git, and PTY features
- Add unit tests for AsyncQueue error paths, PtySession.close,
  Git.checkout without create, Git.add single string,
  Notebook.execCell error case, and PtyStartOptions fields

src/_shared/http.ts

@@ -225,19 +225,22 @@ export class HttpClient {
 	): Promise<T> {
 		const res = await this.rawRequest(method, path, body, opts);
 
-		if (res.status === 204) {
-			return undefined as T;
-		}
-
 		if (!res.ok) {
 			await throwErrorFromResponse(res);
 		}
 
+		if (res.status === 204 || res.headers.get("content-length") === "0") {
+			return undefined as T;
+		}
+
 		if (opts?.asText) {
 			return (await res.text()) as T;
 		}
 
-		return (await res.json()) as T;
+		const text = await res.text();
+		if (!text) return undefined as T;
+
+		return JSON.parse(text) as T;
 	}
 
 	private async rawRequest(

src/_shared/websocket.ts

@@ -46,6 +46,11 @@ export class WsConnection {
 		this.ws.close();
 	}
 
+	/** Closes the WebSocket when used with `await using`. */
+	async [Symbol.asyncDispose](): Promise<void> {
+		this.close();
+	}
+
 	/** Indicates whether the connection has closed or failed. */
 	get isClosed(): boolean {
 		return this.closed;