feat(browser): complete camofox BrowserProvider with tabs, interaction, download capture and control lease

Contracts for browser API and browser.* agent capabilities; adapter implements
close/list/restore sessions, tabs + reconcile, history, click/type/select/scroll/press,
extract, waitForDownload (staged via DownloadSink, sha256), stale-ref guard and
automation/human actor check. testkit mock camofox gains an interactive site
(login redirect, captcha, click-driven page changes, downloads, PNG screenshots).

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

packages/adapters/src/browser/none.ts

@@ -42,5 +42,20 @@ export function createNoneBrowserProvider(): BrowserProvider {
     waitForDownload: unavailable,
     acquireControl: unavailable,
     releaseControl: unavailable,
+    openTab: unavailable,
+    closeTab: unavailable,
+    history: unavailable,
+    select: unavailable,
+    scroll: unavailable,
+    press: unavailable,
+    setController() {
+      throw new BrowserError("unavailable", "未配置浏览器服务");
+    },
+    restoreSession() {
+      throw new BrowserError("unavailable", "未配置浏览器服务");
+    },
+    reconcileTabs: unavailable,
+    sessionInfo: () => null,
+    drain: async () => {},
   };
 }