feat(browser): W4-C BrowserProvider contract and camofox-browser adapter skeleton

- contracts/browser.ts: provider kind, per-capability {supported, verified} flags,
  session/tab/control-lease rows, NavigationBudget, redacted BrowserSnapshot,
  DownloadArtifact with blob/secret refs, BrowserErrorKind
- adapters/browser: BrowserProvider interface, camofox client (health, capabilities
  static + /openapi.json probe, openSession/navigate/snapshot/screenshot; rest
  not_implemented for M2), none provider, redactSnapshot, profile serial lock,
  domain allowlist budget; Bearer access key via BrowserSecretResolver
- testkit/browser: mock camofox server (auth, fixtures with secrets, faults)
- db 0023: browser_provider/session/tab/control_lease with one-active-lease and
  one-live-session-per-profile partial unique indexes; types regenerated
- docs/design/browser-provider.md: contract, camofox OpenAPI 1.17.0 mapping,
  unverified items and M2 prototype checklist; Playwright is not a product browser

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/adapters/src/browser/profile-lock.ts

@@ -0,0 +1,66 @@
+import { BrowserError } from "./errors.ts";
+
+/**
+ * 同一 profile(站点/账号)的浏览器操作串行(REQ §4.4)。
+ * 内存实现只在单进程内有效;多进程/多实例部署需换成持久化实现(PG advisory lock 或
+ * browser_control_lease 表),接口保持不变。
+ */
+export interface ProfileLock {
+  /** 在持有 key 锁期间执行 fn;等待超过 waitMs 抛 BrowserError('lock_timeout') */
+  run<T>(key: string, fn: () => Promise<T>, opts?: { waitMs?: number }): Promise<T>;
+  /** 当前持有或排队中的 key 数量(诊断用) */
+  size(): number;
+}
+
+interface Waiter {
+  resolve: () => void;
+  reject: (e: unknown) => void;
+  timer?: ReturnType<typeof setTimeout>;
+}
+
+export class InMemoryProfileLock implements ProfileLock {
+  private readonly held = new Map<string, Waiter[]>();
+  constructor(private readonly defaultWaitMs = 30_000) {}
+
+  size(): number {
+    return this.held.size;
+  }
+
+  async run<T>(key: string, fn: () => Promise<T>, opts: { waitMs?: number } = {}): Promise<T> {
+    await this.acquire(key, opts.waitMs ?? this.defaultWaitMs);
+    try {
+      return await fn();
+    } finally {
+      this.release(key);
+    }
+  }
+
+  private acquire(key: string, waitMs: number): Promise<void> {
+    const queue = this.held.get(key);
+    if (!queue) {
+      this.held.set(key, []);
+      return Promise.resolve();
+    }
+    return new Promise<void>((resolve, reject) => {
+      const w: Waiter = { resolve, reject };
+      w.timer = setTimeout(() => {
+        const i = queue.indexOf(w);
+        if (i >= 0) queue.splice(i, 1);
+        reject(new BrowserError("lock_timeout", `profile 锁等待超时(${waitMs}ms)`));
+      }, waitMs);
+      queue.push(w);
+    });
+  }
+
+  private release(key: string): void {
+    const queue = this.held.get(key);
+    if (!queue) return;
+    const next = queue.shift();
+    if (!next) {
+      this.held.delete(key);
+      return;
+    }
+    if (next.timer) clearTimeout(next.timer);
+    next.resolve();
+  }
+}