Merge branch 'stack/agent-profiles-5-web-ui' into stack/agent-profiles-8-authoring

The composer's preset seat stays removed here — this layer moved it to the
hero chip and the session-header action — so only the model seat takes the
`modelSeatLocked` narrowing master introduced.

Conflicts:
	apps/web/tests/snapshots/*/*.expected.md
	packages/client/connection/README.md
	packages/client/connection/README.zh.md
	packages/client/ui-conversation/src/client/skeleton/InputBar.tsx
	packages/host/apiproxy/src/fetch/client.ts

apps/web/tests/snapshots/models-settings/declared.expected.md

@@ -0,0 +1,31 @@
+- dialog "设置":
+  - navigation:
+    - text: 设置
+    - button "通用设置":
+      - img
+      - text: 通用设置
+    - button "模型":
+      - img
+      - text: 模型
+  - button "打开配置文件"
+  - button "关闭":
+    - img
+    - text: 关闭
+  - heading "模型" [level=2]
+  - paragraph: 填入各提供方的 API 密钥即可使用其模型。
+  - list:
+    - listitem:
+      - text: minimax-cn
+      - img "API 密钥已配置"
+      - button "编辑 minimax-cn": 编辑
+      - button "删除 minimax-cn": 删除
+    - listitem:
+      - text: Acme Gateway 自定义
+      - button "编辑 Acme Gateway (acme-gateway)": 编辑
+      - button "删除 Acme Gateway (acme-gateway)": 删除
+  - button "添加提供方":
+    - img
+    - text: 添加提供方
+  - button "添加自定义提供方":
+    - img
+    - text: 添加自定义提供方