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).

tests/test_conductor_tech_lead.py

@@ -1,6 +1,7 @@
 import unittest
 from unittest.mock import patch
 from src import conductor_tech_lead
+from src.models import Ticket
 from src.result_types import Result
 import pytest
 
@@ -30,28 +31,28 @@ class TestConductorTechLead(unittest.TestCase):
 class TestTopologicalSort(unittest.TestCase):
  def test_topological_sort_linear(self) -> None:
   tickets = [
-   {"id": "t2", "depends_on": ["t1"]},
-   {"id": "t1", "depends_on": []},
+   Ticket(id="t2", description="t2", depends_on=["t1"]),
+   Ticket(id="t1", description="t1", depends_on=[]),
   ]
   sorted_tickets = conductor_tech_lead.topological_sort(tickets)
-  self.assertEqual(sorted_tickets[0]['id'], "t1")
-  self.assertEqual(sorted_tickets[1]['id'], "t2")
+  self.assertEqual(sorted_tickets[0].id, "t1")
+  self.assertEqual(sorted_tickets[1].id, "t2")
 
  def test_topological_sort_complex(self) -> None:
   tickets = [
-   {"id": "t3", "depends_on": ["t1", "t2"]},
-   {"id": "t1", "depends_on": []},
-   {"id": "t2", "depends_on": ["t1"]},
+   Ticket(id="t3", description="t3", depends_on=["t1", "t2"]),
+   Ticket(id="t1", description="t1", depends_on=[]),
+   Ticket(id="t2", description="t2", depends_on=["t1"]),
   ]
   sorted_tickets = conductor_tech_lead.topological_sort(tickets)
-  self.assertEqual(sorted_tickets[0]['id'], "t1")
-  self.assertEqual(sorted_tickets[1]['id'], "t2")
-  self.assertEqual(sorted_tickets[2]['id'], "t3")
+  self.assertEqual(sorted_tickets[0].id, "t1")
+  self.assertEqual(sorted_tickets[1].id, "t2")
+  self.assertEqual(sorted_tickets[2].id, "t3")
 
  def test_topological_sort_cycle(self) -> None:
   tickets = [
-   {"id": "t1", "depends_on": ["t2"]},
-   {"id": "t2", "depends_on": ["t1"]},
+   Ticket(id="t1", description="t1", depends_on=["t2"]),
+   Ticket(id="t2", description="t2", depends_on=["t1"]),
   ]
   with self.assertRaises(ValueError) as cm:
    conductor_tech_lead.topological_sort(tickets)
@@ -65,7 +66,7 @@ class TestTopologicalSort(unittest.TestCase):
   # If a ticket depends on something not in the list, we should handle it or let it fail.
   # The TrackDAG silently ignores missing dependencies, causing cycle detection to trigger.
   tickets = [
-   {"id": "t1", "depends_on": ["missing"]},
+   Ticket(id="t1", description="t1", depends_on=["missing"]),
   ]
   # Currently this raises ValueError due to cycle detection on incomplete sort
   with self.assertRaises(ValueError):
@@ -73,12 +74,12 @@ class TestTopologicalSort(unittest.TestCase):
 
 def test_topological_sort_vlog(vlogger) -> None:
  tickets = [
-  {"id": "t2", "depends_on": ["t1"]},
-  {"id": "t1", "depends_on": []},
+  Ticket(id="t2", description="t2", depends_on=["t1"]),
+  Ticket(id="t1", description="t1", depends_on=[]),
  ]
  vlogger.log_state("Input Order", ["t2", "t1"], ["t2", "t1"])
  sorted_tickets = conductor_tech_lead.topological_sort(tickets)
- result_ids = [t['id'] for t in sorted_tickets]
+ result_ids = [t.id for t in sorted_tickets]
  vlogger.log_state("Sorted Order", "N/A", result_ids)
  assert result_ids == ["t1", "t2"]
  vlogger.finalize("Topological Sort Verification", "PASS", "Linear dependencies correctly ordered.")