feat(R07): task repository, schedule calculator, Qt clock adapter, task/AI-planner services

Team Hoa, EPIC R07 (Scheduling & Workflow Runtime) - Team Hoa scope only
(R07-T01 -> T05; R07-T06 Co4EWorkflowService is Team Nam's).

- R07-T01: infrastructure/persistence/json/task_repository_impl.py wraps
  core/tasks.py's CRUD; core/tasks.py::save_task now writes through
  atomic_write.write_json (same durability fix as R06-T02, save_task was
  still doing a plain write_text).
- R07-T02: domain/tasks/schedule_calculator.py::ScheduleCalculator - the
  cron/interval/daily/weekly/monthly due-time math extracted from
  core/tasks.py, pure Python with is_holiday/make_cron injected so domain/
  never imports core (ADR-001 I2). core/tasks.py keeps its old function
  names as thin wrappers so every existing caller is unchanged. This was
  previously untested; now has its own unit suite.
- R07-T03: infrastructure/qt/qt_scheduler_clock.py::QtSchedulerClock wraps
  the QTimer TaskScheduler used to own directly, injected via a new
  `clock=` constructor param (defaults to a real one). Originally planned
  at platform/qt/... ; moved after confirming that name shadows the
  stdlib platform module (used by core/windows_sandbox_vm.py,
  core/appcontainer_sandbox.py) whenever the repo root is on sys.path.
  tests/fakes/fake_clock.py lets scheduler dispatch be tested tick-by-tick
  with no Qt event loop.
- R07-T04: application/scheduling/task_application_service.py centralizes
  run_now/duplicate/pause/delete/bulk_delete and the Kanban drag-drop
  business rules (move_to_status), currently only reachable by driving
  the real ui/schedule_task_tab.py widget.
- R07-T05: application/scheduling/ai_task_planner_service.py wraps
  core/ai_task_planner.py::plan_tasks and core/task_import.py::import_tasks
  as a seam, plus the attachment-stamping step that used to only exist
  inside the AI-create dialog's worker closure.

pytest: 328 pass (same 4 pre-existing failures as the R05/R06 baseline,
unrelated to this work - see docs/refactor/BaoCao_TeamHoa_R05_R06.md).
scripts/check_imports.py: PASS.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

application/scheduling/ai_task_planner_service.py

@@ -0,0 +1,94 @@
+"""AiTaskPlannerService - AI-generate / import task lists, outside the widget
+(R07-T05).
+
+``ui/schedule_task_tab.py``'s ``_AiCreateDialog`` already delegates the
+actual planning to two existing pure functions —
+``core/ai_task_planner.py::plan_tasks`` (natural-language description ->
+task dicts, via the active provider) and
+``core/task_import.py::import_tasks`` (Excel/CSV/JSON -> task dicts) — so
+this service does not reimplement either. What it DOES own is one small
+piece of business logic that currently only exists inside the dialog's
+``AgentWorker`` job closure (``_generate``'s ``job()``): every AI-generated
+task must carry the SAME file/link attachments the user attached to the
+request, so they're available again at run time, not just visible to the
+planner while it drafts the task list. Leaving that step trapped in a Qt
+worker closure means it can only be exercised by driving the real dialog;
+here it's a plain, independently testable method.
+
+Pure Python: no Qt import. The provider is a constructor-injected factory
+(``() -> Provider``, no arguments — matches ``AppContext.build_active_
+provider``), the same dependency-inversion shape
+``application/conversations/conversation_application_service.py`` (R04-T03)
+uses for ITS provider factory.
+"""
+from __future__ import annotations
+
+from pathlib import Path
+from typing import Any, Callable, Dict, List, Optional, Sequence, Union
+
+ProviderFactory = Callable[[], Any]
+CancelFn = Callable[[], bool]
+
+
+class AiTaskPlannerService:
+    """AI task generation + file/Excel/CSV/JSON import, for
+    ``presentation/scheduling/ai_task_creator_dialog.py`` and
+    ``ai_task_import_dialog.py`` (R08-T11) to call instead of importing
+    ``core.ai_task_planner``/``core.task_import`` directly.
+
+    Args:
+        provider_factory: ``() -> Provider``. Production passes
+            ``AppContext.build_active_provider``; tests pass a lambda
+            returning a :class:`FakeProvider`.
+    """
+
+    def __init__(self, provider_factory: Optional[ProviderFactory] = None) -> None:
+        self._provider_factory = provider_factory
+
+    def plan(
+        self,
+        description: str,
+        *,
+        file_paths: Sequence[str] = (),
+        links: Sequence[str] = (),
+        provider: Any = None,
+        cancel: Optional[CancelFn] = None,
+    ) -> List[Dict[str, Any]]:
+        """Turn ``description`` into a list of NOT-yet-saved task dicts.
+
+        ``provider`` overrides the constructor's factory for this one call
+        (useful for tests, or a caller that already resolved a provider);
+        omit it to use the injected factory. Raises ``RuntimeError`` when
+        no provider is available at all, or when the model's reply had no
+        parseable task list (same error ``core.ai_task_planner.plan_tasks``
+        already raises).
+        """
+        resolved = provider if provider is not None else self._resolve_provider()
+        from cowork_local.core.ai_task_planner import plan_tasks
+
+        planned = plan_tasks(resolved, description, cancel=cancel)
+        # Attachments apply to EVERY generated task so they're still there
+        # when the task actually runs, not just while the planner drafts it
+        # (see module docstring — this used to only happen inside the
+        # dialog's worker closure).
+        for task in planned:
+            task["input"]["file_paths"] = list(file_paths)
+            task["input"]["links"] = list(links)
+        return planned
+
+    def import_file(self, path: Union[str, Path]) -> List[Dict[str, Any]]:
+        """Excel/CSV/JSON -> NOT-yet-saved task dicts, auto-chained in file
+        order. Raises ``ValueError`` with a human-readable message on an
+        unusable/unsupported file (same contract
+        ``core.task_import.import_tasks`` already has)."""
+        from cowork_local.core.task_import import import_tasks
+
+        return import_tasks(path)
+
+    def _resolve_provider(self) -> Any:
+        if self._provider_factory is None:
+            raise RuntimeError("No provider available to plan tasks.")
+        return self._provider_factory()
+
+
+__all__ = ["AiTaskPlannerService"]