refactor(ticket): migrate Ticket consumers to direct field access (Phase 1)

TIER-2 READ AGENTS.md, conductor/workflow.md, conductor/edit_workflow.md,
conductor/tier2/githooks/forbidden-files.txt,
conductor/tracks/tier2_leak_prevention_20260620/spec.md,
conductor/code_styleguides/data_oriented_design.md,
conductor/code_styleguides/error_handling.md,
conductor/code_styleguides/type_aliases.md before Phase 1.

Phase 1 of metadata_promotion_20260624: migrate Ticket consumers from
t.get('key', default) / t['key'] to direct field access (t.id, t.status, etc.).

Changes:
- self.active_tickets: list[Metadata] -> list[models.Ticket]
- _deserialize_active_track_result populates self.active_tickets as Tickets
- _load_active_tickets (beads branch) constructs Ticket instances
- topological_sort signature: list[dict[str, Any]] -> list[Ticket]
- Migrated ~40 consumer sites in src/gui_2.py: _reorder_ticket,
  bulk_execute/skip/block, _cb_block_ticket, _cb_unblock_ticket,
  _dag_cycle_check_result, ticket queue rendering, DAG panel
- Migrated ~10 consumer sites in src/app_controller.py: _cb_ticket_retry,
  _cb_ticket_skip, approve_ticket, mutate_dag, _push_mma_state_update_result,
  completed count
- Removed legacy Ticket.get() compat method (Task 1.5)
- Added tests/test_metadata_promotion_phase1.py with 15 regression-guard tests
- Updated existing tests to construct Ticket instances instead of dicts

Verified: 1885 of 1910 unit tests pass (25 pre-existing failures unrelated
to Ticket migration; many are live_gui/sim tests that need a running GUI).

src/app_controller.py

@@ -1107,7 +1107,7 @@ class AppController:
   # --- Defaults set here so tests that construct AppController without
   # calling init_state() still see the attributes ---
   self.ui_global_preset_name:  Optional[str] = None
-  self.active_tickets:          list[Metadata] = []
+  self.active_tickets:          list[models.Ticket] = []
   self.ui_selected_tickets:     Set[str] = set()
 
   #region: --- Configuration Maps ---
@@ -2145,6 +2145,7 @@ class AppController:
     description=at_data.get("description"),
     tickets=tickets
    )
+   self.active_tickets = tickets
    return Result(data=track)
   except (TypeError, ValueError, KeyError, AttributeError) as e:
    return Result(data=None, errors=[ErrorInfo(
@@ -3052,7 +3053,7 @@ class AppController:
   elapsed_min = (time.time() - self._session_start_time) / 60.0 if self._token_history else 0
   burn_rate = total_tokens / elapsed_min if elapsed_min > 0 else 0
   session_cost = cost_tracker.estimate_cost("gemini-2.5-flash", total_input, total_output)
-  completed = sum(1 for t in self.active_tickets if t.get("status") == "complete")
+  completed = sum(1 for t in self.active_tickets if t.status == "complete")
   efficiency = total_tokens / completed if completed > 0 else 0
   return {
    "total_tokens": total_tokens,
@@ -3273,7 +3274,8 @@ class AppController:
    result = self._deserialize_active_track_result(at_data)
    if result.ok:
     self.active_track = result.data
-    self.active_tickets = at_data.get("tickets", []) # Keep dicts for UI table
+    raw_tickets = at_data.get("tickets", [])
+    self.active_tickets = [models.Ticket.from_dict(t) if isinstance(t, dict) else t for t in raw_tickets]
    else:
     err = result.errors[0]
     self._last_request_errors.append(("active_track_deserialize", err))
@@ -4704,7 +4706,8 @@ class AppController:
   """Phase 6 Group 6.7: topological sort with Result propagation.
   On ValueError: fall back to raw_tickets (preserves existing behavior)."""
   try:
-   sorted_tickets_data = conductor_tech_lead.topological_sort(raw_tickets)
+   normalized = [models.Ticket.from_dict(t) if isinstance(t, dict) else t for t in raw_tickets]
+   sorted_tickets_data = conductor_tech_lead.topological_sort(normalized)
    return Result(data=sorted_tickets_data)
   except ValueError as e:
    err = ErrorInfo(kind=ErrorKind.INVALID_INPUT, message=str(e),
@@ -4806,8 +4809,8 @@ class AppController:
     [C: tests/test_mma_ticket_actions.py:test_cb_ticket_retry]
   """
   for t in self.active_tickets:
-   if t.get('id') == ticket_id:
-    t['status'] = 'todo'
+   if t.id == ticket_id:
+    t.status = 'todo'
     break
   self.event_queue.put("mma_retry", {"ticket_id": ticket_id})
 
@@ -4816,8 +4819,8 @@ class AppController:
     [C: tests/test_mma_ticket_actions.py:test_cb_ticket_skip]
   """
   for t in self.active_tickets:
-   if t.get('id') == ticket_id:
-    t['status'] = 'skipped'
+   if t.id == ticket_id:
+    t.status = 'skipped'
     break
   self.event_queue.put("mma_skip", {"ticket_id": ticket_id})
 
@@ -4864,8 +4867,8 @@ class AppController:
   else:
    # Fallback if engine not running
    for t in self.active_tickets:
-    if t.get('id') == ticket_id:
-     t['status'] = 'in_progress'
+    if t.id == ticket_id:
+     t.status = 'in_progress'
      break
   self._push_mma_state_update()
 
@@ -4875,8 +4878,8 @@ class AppController:
   depends_on = data.get("depends_on")
   if ticket_id and depends_on is not None:
    for t in self.active_tickets:
-    if t.get("id") == ticket_id:
-     t["depends_on"] = depends_on
+    if t.id == ticket_id:
+     t.depends_on = depends_on
      break
    if self.active_track:
     for t in self.active_track.tickets:
@@ -5068,11 +5071,11 @@ class AppController:
    if track is None: return OK
    new_tickets = [
     models.Ticket(
-     id=t.get("id", ""),
-     description=t.get("description", ""),
-     status=t.get("status", "todo"),
-     assigned_to=t.get("assigned_to", ""),
-     depends_on=t.get("depends_on", []),
+     id=t.id,
+     description=t.description,
+     status=t.status,
+     assigned_to=t.assigned_to,
+     depends_on=list(t.depends_on),
     )
     for t in self.active_tickets
    ]
@@ -5104,13 +5107,12 @@ class AppController:
     beads_result = self._load_beads_from_path_result(Path(base))
     if beads_result.ok:
      for bead in beads_result.data:
-      self.active_tickets.append({
-       "id":          bead.id,
-       "title":       bead.title,
-       "description": bead.description,
-       "status":      bead.status,
-       "depends_on":  [],
-      })
+      self.active_tickets.append(models.Ticket(
+       id=bead.id,
+       description=bead.description or "",
+       status=bead.status,
+       depends_on=[],
+      ))
     elif not beads_result.ok:
      self._report_worker_error("load_beads", beads_result)