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/__tests__/lane-sources.test.js

@@ -205,6 +205,9 @@ describe("lane-sources instructions and launch", () => {
     assert.equal(argv[5], "--permission-mode");
     assert.ok(!argv.some((a) => a.startsWith("--append-system-prompt")));
     assert.ok(newSession.includes("CLAUDE_CODE_ADDITIONAL_DIRECTORIES_CLAUDE_MD=1"));
+    // Claude Code hides its task tools from newer models without this, and the
+    // chat Progress panel is drawn from those calls.
+    assert.ok(newSession.includes("CLAUDE_CODE_ENABLE_TODO_TOOLS=1"));
     assert.deepEqual(fs.readdirSync(dir), ["CLAUDE.md"]);
     const text = fs.readFileSync(path.join(dir, "CLAUDE.md"), "utf8");
     assert.match(text, /^- always answer in Vietnamese/);