fix(render_task_dag_panel): prevent AttributeError on dict leftover tickets

Test_undo_redo_lifecycle was failing in tier-3 batch because:
1. The prior test (test_mma_concurrent_tracks_sim) leaves dict-typed
   ticket entries in app.active_tickets (via the Add Ticket form path
   that creates Ticket dicts, not Ticket dataclass instances).
2. render_task_dag_panel iterates app.active_tickets and does t.id,
   t.status, t.target_file on each element. A dict element raises
   AttributeError on .id, and imgui-node-editor's internal state
   becomes unbalanced, throwing 'Missing PopID()' on subsequent frames.
3. The ImGui assertion kills the render loop, _handle_history_logic
   stops firing, no snapshot push happens, undo stack stays empty,
   undo test fails with can_undo=False.

Fix in src/gui_2.py:
- Pre-filter app.active_tickets to a local _tickets list that drops
  non-Ticket elements (no .id and .status attrs). The unfiltered list
  is still authoritative for tests that read it via api_hooks.
- Replace app.active_tickets references in the for-loops with _tickets.
- Wrap the entire body in try/except as a second line of defense for
  any other ImGui state corruption. Drain to _last_request_errors.

Fix in src/app_controller.py:
- btn_reset now also syncs app.temperature/top_p/max_tokens/ui_ai_input
  from the controller's reset values. Without this, prior test setattr
  calls leave stale app attrs that the snapshot push captures as the
  'reset' baseline.
- btn_reset also clears app.active_tickets, app.active_track,
  app.proposed_tracks, app.mma_streams. Same reason: prior tests in
  the same live_gui session pollute these, and the next test inherits
  the dirty state.

Verified: all 3 test_undo_redo_sim tests (test_undo_redo_lifecycle,
test_undo_redo_discussion_mutation, test_undo_redo_context_mutation)
now pass in tier-3 batch (previously only passed in isolation). The
single remaining tier-3 failure is test_visual_sim_mma_v2 which fails
because the gemini_cli mock service doesn't respond with proposed
tracks in batch context - unrelated to the render loop.

src/app_controller.py

@@ -3954,10 +3954,18 @@ class AppController:
   self.temperature = 0.0
   self.top_p = 1.0
   self.max_tokens = 8192
-  # Clear undo/redo history so the next session starts fresh. Without
-  # this, prior tests in the same live_gui session leave stale entries
-  # that interfere with tests like tests/test_undo_redo_sim.py that
-  # assume btn_reset provides a clean history baseline.
+  # Clear undo/redo history AND sync the App's snapshot attrs so the
+  # next session starts fresh. Without the App-side sync, prior tests in
+  # the same live_gui session leave ai_input/temperature/etc. set on the
+  # App (via api_hooks setattr going to App, not Controller), the
+  # snapshot logic reads the leftover App values, pushes the leftover as
+  # the "reset" baseline to the undo stack, and test_undo_redo_lifecycle's
+  # undo restores the leftover instead of the post-reset state.
+  # We also clear app.active_tickets (and related) because leftover
+  # tickets from prior tests drive render_task_dag_panel to call
+  # imgui-node-editor with stale state, which can fire "Missing PopID()"
+  # and kill the render loop (test_undo_redo_lifecycle regression on
+  # 2026-07-01 — see docs/reports/TRACK_RESULT_MIGRATION_POLISH_20260630.md).
   if hasattr(self, 'hook_server') and self.hook_server and getattr(self.hook_server, 'app', None) is not None:
    app = self.hook_server.app
    if hasattr(app, 'history'):
@@ -3966,6 +3974,15 @@ class AppController:
    if hasattr(app, '_last_ui_snapshot'):   app._last_ui_snapshot = None
    if hasattr(app, '_pending_snapshot'):   app._pending_snapshot = False
    if hasattr(app, '_state_to_push'):      app._state_to_push  = None
+   if hasattr(app, '_snapshot_timer'):     app._snapshot_timer = 0.0
+   if hasattr(app, 'temperature'):          app.temperature = self.temperature
+   if hasattr(app, 'top_p'):                app.top_p       = self.top_p
+   if hasattr(app, 'max_tokens'):          app.max_tokens  = self.max_tokens
+   if hasattr(app, 'ui_ai_input'):         app.ui_ai_input = ""
+   if hasattr(app, 'active_tickets'):      app.active_tickets = []
+   if hasattr(app, 'active_track'):        app.active_track   = None
+   if hasattr(app, 'proposed_tracks'):     app.proposed_tracks = []
+   if hasattr(app, 'mma_streams'):         app.mma_streams.clear()
 
  def _handle_compress_discussion(self) -> None:
   def worker() -> "Result[None]":