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

server/lib/pty-run.js

@@ -640,6 +640,11 @@ function spawnRun(args) {
     ...(entry.launcher === "claude" && systemPromptFile
       ? { CLAUDE_CODE_ADDITIONAL_DIRECTORIES_CLAUDE_MD: "1" }
       : {}),
+    // Claude Code hides TaskCreate/TaskUpdate from its newer models unless
+    // this is set, and those calls are all the chat Progress panel draws
+    // (routes/sessions.js sessionOutline). A user's settings.json `env` still
+    // wins, so `"0"` there turns them back off.
+    ...(entry.launcher === "claude" ? { CLAUDE_CODE_ENABLE_TODO_TOOLS: "1" } : {}),
     // No CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN: an inline claude duplicated its
     // output whenever the pane narrowed (tmux re-wraps the full-width rules and
     // pushes lines into history its redraw cannot clear). The user's own