fix(connect): passively-discovered tabs no longer steal the active tab

After connect+grouping worked, follow-up eval/get-title/screenshot drifted to a
foreign tab: on a shared browser, Target.targetCreated events for tabs the user
or OTHER agent sessions open stream in and are drained on every command. The
drain path routed them through add_page(), which sets active_page_index to the
new page — so the session's active tab silently jumped to a foreign tab and its
commands landed there.

Add BrowserManager::add_background_page() (push without touching active, dedup by
target_id) and use it in the event-drain path. Explicit opens (tab new, the
add-and-switch paths) keep using add_page() and still focus the new tab.

Closes the last gap in concurrent multi-agent: each session now drives its OWN
tab regardless of other sessions'/the user's tab activity.

cli/src/native/actions.rs

@@ -672,7 +672,10 @@ impl DaemonState {
                     }
 
                     let tab_id = mgr.assign_tab_id();
-                    mgr.add_page(super::browser::PageInfo {
+                    // Passively discovered (event-driven) — must NOT steal the
+                    // active tab, or a foreign/user/other-session tab opening
+                    // hijacks this session's eval/screenshot target.
+                    mgr.add_background_page(super::browser::PageInfo {
                         tab_id,
                         label: None,
                         target_id: te.target_info.target_id.clone(),

cli/src/native/browser.rs

@@ -1532,6 +1532,21 @@ impl BrowserManager {
         self.active_page_index = index;
     }
 
+    /// Add a passively-discovered page WITHOUT changing the active tab.
+    ///
+    /// On a shared browser (ab-connect), `Target.targetCreated` events stream in
+    /// for tabs the user or OTHER agent sessions open. Those are drained on every
+    /// command; routing them through `add_page` made the active tab silently jump
+    /// to a foreign tab, so the session's own `eval`/`get title`/`screenshot`
+    /// landed on the wrong page. Passively-tracked pages must not steal focus —
+    /// only explicit opens (`tab new`, switch) set the active tab.
+    pub fn add_background_page(&mut self, page: PageInfo) {
+        if self.pages.iter().any(|p| p.target_id == page.target_id) {
+            return;
+        }
+        self.pages.push(page);
+    }
+
     pub fn update_page_target_info(&mut self, target: &TargetInfo) -> bool {
         update_page_target_info_in_pages(&mut self.pages, target)
     }