feat(baoyu-fetch): add X session cookie sidecar and graceful Chrome lifecycle

Add cookie sidecar to export/restore X session cookies across runs.
Implement graceful Browser.close via WebSocket before falling back to kill.
Auto-detect and clean stale Chrome profile lock artifacts on launch failure.
Wait for X session readiness (auth_token + ct0) before auto-continuing login flows.

packages/baoyu-fetch/src/__tests__/x-session.test.ts

@@ -0,0 +1,28 @@
+import { describe, expect, test } from "bun:test";
+
+import { buildXSessionCookieMap, hasRequiredXSessionCookies } from "../adapters/x/session";
+
+describe("X session helpers", () => {
+  test("keeps non-empty X session cookies", () => {
+    expect(
+      buildXSessionCookieMap([
+        { name: "auth_token", value: "auth" },
+        { name: "ct0", value: "csrf" },
+        { name: "twid", value: "u=123" },
+        { name: "ct0", value: "" },
+        { name: "", value: "ignored" },
+        { name: "gt", value: undefined },
+      ]),
+    ).toEqual({
+      auth_token: "auth",
+      ct0: "csrf",
+      twid: "u=123",
+    });
+  });
+
+  test("requires auth_token and ct0 for a ready X session", () => {
+    expect(hasRequiredXSessionCookies({ auth_token: "auth" })).toBe(false);
+    expect(hasRequiredXSessionCookies({ ct0: "csrf" })).toBe(false);
+    expect(hasRequiredXSessionCookies({ auth_token: "auth", ct0: "csrf" })).toBe(true);
+  });
+});