refactor(app_controller): migrate _push_mma_state_update + _load_beads to Result helpers (Phase 7)

Tasks 7.4 + 7.5: Migrate two more strict-violation sites to proper
Result[T] propagation:
- _push_mma_state_update: legacy wrapper preserved (fire-and-forget
  semantics) but routes errors through _report_worker_error. New
  _push_mma_state_update_result helper returns Result[None].
- _load_active_tickets.beads inner: extracted to
  _load_beads_from_path_result helper; outer merges errors via
  _report_worker_error.

Per Phase 7 spec 22.5.3 + 22.5.4:
- Each helper catches OSError/IOError/ValueError/TypeError/KeyError/
  AttributeError -> ErrorInfo(original=e).
- Drain is Pattern 4 telemetry via _report_worker_error
  (Pattern 4 = in-process telemetry buffer that sub-track 4 forwards
  to GUI per error_handling.md:421).

TIER-2 READ conductor/code_styleguides/error_handling.md end-to-end
before this commit.

tests/test_app_controller_result.py

@@ -575,17 +575,21 @@ def test_push_mma_state_update_records_error_in_state():
 
 def test_load_beads_from_path_returns_result():
  """
- Phase 7 Task 7.5: _load_beads_from_path_result returns Result[List[Ticket]].
+ Phase 7 Task 7.5: _load_beads_from_path_result returns Result[List[Bead]].
  On error: ErrorInfo(original=e).
  """
+ from pathlib import Path
  from src.app_controller import AppController
+ from unittest.mock import MagicMock
  ctrl = AppController()
  assert hasattr(ctrl, "_load_beads_from_path_result"), (
   "AppController must have _load_beads_from_path_result helper per Phase 7."
  )
- # Success path returns Result with empty list when no tickets
- with patch("src.app_controller.beads_client.list_tickets", return_value=[]):
-  result = ctrl._load_beads_from_path_result("/tmp/fake_beads_path")
+ # Success path returns Result with empty list when not initialized
+ fake_bclient = MagicMock()
+ fake_bclient.is_initialized.return_value = False
+ with patch("src.beads_client.BeadsClient", return_value=fake_bclient):
+  result = ctrl._load_beads_from_path_result(Path("/tmp/fake_beads_path"))
  assert isinstance(result, Result)
  assert result.ok is True
  assert result.data == []
@@ -593,14 +597,16 @@ def test_load_beads_from_path_returns_result():
 
 def test_load_beads_from_path_records_error_on_failure():
  """
- Phase 7 Task 7.5: when beads_client.list_tickets raises, the helper returns
+ Phase 7 Task 7.5: when BeadsClient constructor raises, the helper returns
  Result with ErrorInfo(original=e).
  """
+ from pathlib import Path
  from src.app_controller import AppController
+ from unittest.mock import MagicMock
  ctrl = AppController()
- with patch("src.app_controller.beads_client.list_tickets",
+ with patch("src.beads_client.BeadsClient",
      side_effect=OSError("beads path not found")):
-  result = ctrl._load_beads_from_path_result("/tmp/nonexistent")
+  result = ctrl._load_beads_from_path_result(Path("/tmp/nonexistent"))
  assert isinstance(result, Result)
  assert result.ok is False
  assert len(result.errors) == 1