feat(chat): terminal chat parity for every tool; Desktop-like artifacts

- The chat over a terminal pane now covers Claude, Codex, omp, Cursor and
  Antigravity: Cursor's agent transcript and agy's step log
  (brain/<id>/.system_generated/logs/transcript_full.jsonl) are read as
  conversations; Cursor sessions are claimed by their workspace
- Replies appear as soon as they are written: the projects-tree watcher
  broadcasts `transcript_changed` (at most every 250 ms per session) and the
  chat re-reads the transcript while the terminal underneath draws
- Stop shows from the pane's own busy line (Claude/Codex `esc to interrupt`,
  agy `… esc to cancel`), or fresh output for omp/Cursor — no hooks needed
- Permission prompts read off the terminal become a card with the tool, its
  command and "Deny with a note"; Codex gets Permission mode / Model buttons
  that open its own numbered pickers, answered from the menu card
- Artifacts: cards for pages/documents/diagrams/tables/React components, a
  Preview | Code panel with versions, copy, download, save to the Artifacts
  Hub, full screen; sandboxed iframes without allow-same-origin
- Claude panes get CLAUDE_CODE_ENABLE_TODO_TOOLS=1 so the Progress panel has a
  plan; multi-question pane menus read their Next row and question tabs
- The realtime chat bridge (structured stdio, /api/chat-bridge, /ws-chat)
  from the unreleased ad9d475 is not kept

client/src/lib/chatUi.ts

@@ -1,6 +1,7 @@
 /**
- * @file chatUi.ts — whether a Claude/Codex session shows as a chat
- * (`PaneChat`, like Claude Desktop) or as its terminal. Each SESSION has its
+ * @file chatUi.ts — which tools' terminal panes have a Chat view
+ * (`CHAT_TOOLS`), and whether such a session shows as a chat (`PaneChat`,
+ * like Claude Desktop) or as its terminal. Each SESSION has its
  * own view (`useSessionChat`, toggled by `setSessionChat` from the pane's
  * chat/terminal button), kept in this browser's localStorage
  * (`agenthub.chatUi.sessions`, the newest `MAX_VIEWS`). The account's Chat UI
@@ -18,6 +19,19 @@ import { api } from "./api";
 
 export const CHAT_UI_KEY = "agenthub.chatUi";
 
+/** The tools whose terminal pane can show a chat: each one's pane learns its
+ *  session id (Claude's `--session-id`, the others' pollers through
+ *  `claimToolSessions`) and the server reads that session's conversation
+ *  (`GET /api/sessions/:id/transcript`). omp and Cursor send no hooks, so
+ *  their chat has no Stop button and follows at the pollers' pace. */
+export const CHAT_TOOLS: ReadonlySet<string> = new Set([
+  "claude",
+  "codex",
+  "omp",
+  "cursor",
+  "antigravity",
+]);
+
 export const VIEWS_KEY = "agenthub.chatUi.sessions";
 const MAX_VIEWS = 200;