Merge master into subagent usage branch

# Conflicts:
#	.agents/notes/implemented/feature/2026-07-27-web-subagent-conversations.i18n.yaml
#	.agents/notes/implemented/feature/2026-07-27-web-subagent-conversations.md
#	.agents/notes/implemented/feature/2026-07-27-web-subagent-conversations.zh.md
#	apps/web/tests/snapshots/subagent-conversation/tree.expected.md
#	apps/web/tests/subagent-conversation.e2e.ts
#	packages/client/ui-subagent/src/client/SubagentCatalogAction.tsx

apps/web/tests/snapshots/subagent-conversation/nested.expected.md

@@ -14,5 +14,5 @@
 - button "Branch into a new conversation":
   - img
 - status:
-  - strong: 此子代理暂时只读
-  - text: 父会话当前不在线，重新打开父会话后即可继续发送消息。
+  - strong: This subagent is read-only for now
+  - text: The parent session is offline; reopen it to continue sending messages.

apps/web/tests/snapshots/subagent-conversation/stale-catalog.expected.md

@@ -0,0 +1,3 @@
+- tree "Subagent sessions":
+  - treeitem "Loading subagents" [disabled] [level=1]: Loading subagents…
+  - treeitem "Loading subagents" [disabled] [level=1]: Loading subagents…

apps/web/tests/snapshots/subagent-conversation/tree.expected.md

@@ -1,8 +1,8 @@
-- tree "子代理会话":
-  - treeitem "event-sourcing researcher Explain event sourcing in one · 可继续 · 当前未运行 7.9K tok · 2秒" [expanded] [level=1]:
-    - button "收起 event-sourcing researcher 的下级子代理":
+- tree "Subagent sessions":
+  - treeitem "event-sourcing researcher Explain event sourcing in one · continuable · not running 7.9K tok · {{duration}}" [expanded] [level=1]:
+    - button "Collapse event-sourcing researcher descendants":
       - img
-    - text: event-sourcing researcher Explain event sourcing in one · 可继续 · 当前未运行 7.9K tok · 2秒
+    - text: event-sourcing researcher Explain event sourcing in one · continuable · not running 7.9K tok · {{duration}}
   - group:
-    - treeitem "example editor 可继续 · 当前未运行 0 tok · 0秒" [level=2]
-  - treeitem "event-sourcing reviewer 一次性 · 当前未运行 0 tok · 0秒" [level=1]
+    - treeitem "example editor continuable · not running 0 tok · {{duration}}" [level=2]
+  - treeitem "event-sourcing reviewer one-shot · not running 0 tok · {{duration}}" [level=1]

apps/web/tests/snapshots/subagent-conversation/ui.expected.md

@@ -3,8 +3,8 @@
     - button "Ask a research subagent to"
     - text: /
     - button "event-sourcing researcher" [disabled]
-  - button "1 个子代理":
-    - text: 1 个子代理
+  - button "1 subagent":
+    - text: 1 subagent
     - img
   - tablist:
     - tab "Chat" [selected]