feat(feedback): add the Web surface for message feedback

Consume the durable message-feedback sidecar from #2217 in the browser:
per-message Like/Dislike with an optional note, contributed through a
declared assistant-actions slot.

- carry MessageId on finalized AssistantMessageNode so a target is nameable
- declare conversation.chat.assistant-actions and render it in the
  IconActions row between copy and branch
- hold one FeedbackController per Session with per-item ifVersion CAS,
  reconciling a version-conflict from the reply's authoritative item
- mount messageFeedbackRemote alongside goalsRemote

tsconfig.client.json

@@ -68,6 +68,7 @@
     { "path": "./packages/client/ui-subagent" },
     { "path": "./packages/client/ui-task" },
     { "path": "./packages/client/ui-goal" },
+    { "path": "./packages/client/ui-feedback" },
     { "path": "./packages/client/ui-model" },
     { "path": "./packages/client/ui-agent-preset" },
     { "path": "./packages/client/ui-permission" },