feat: surface task execution progress across Host Agent and Cloud

Host Agent now persists step-level execution detail locally (via a real
TaskMetadataStore/Timeline wired into TaskRunner) and reports a bounded
in-progress snapshot piggybacked on lease renewal. Cloud persists that
snapshot per active assignment and exposes it through the existing task
list/detail query path; Cloud Console renders it as a live badge. Host
Agent's local console gains authenticated, read-only task list and
detail/timeline pages (same-origin, server-rendered) with inlined
screenshots.

Also fixes a pre-existing gap in the shared Timeline: the actual
per-step LLM prompt is now recorded instead of the task goal, benefiting
both Runtime and Host Agent consoles. When a host uses the cloud planner
transport, each decide call's prompt and resulting tool decision are
durably logged in a new planner_decision_log table (with bounded
retention) and browsable from Cloud Console; direct-transport hosts
explicitly surface a "not reported" state.

Includes Alembic migrations 0008 (progress columns on scheduled_tasks)
and 0009 (planner_decision_log), bounded Host-Agent-local retention,
dual-backend repository parity, and Vitest + pytest coverage. Task 6.5
(manual end-to-end device verification) remains.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/device-host-agent/host_agent/assignment.py

@@ -8,6 +8,7 @@ from cloud.internal_api.models import AssignmentModel
 from core.models import Task
 from host_agent.execution import ExecutionFactories
 from host_agent.planner_context import bind_planner_execution_context
+from host_agent.progress import TaskProgressHolder, TaskProgressSnapshot
 
 
 @dataclass(frozen=True)
@@ -20,6 +21,11 @@ class AssignmentExecutionResult:
 class AssignmentExecutor:
     def __init__(self, factories: ExecutionFactories) -> None:
         self.factories = factories
+        self._progress = TaskProgressHolder()
+
+    def latest_progress(self) -> TaskProgressSnapshot | None:
+        """Latest step progress reported by the currently-running assignment."""
+        return self._progress.snapshot()
 
     def execute(
         self,
@@ -27,6 +33,7 @@ class AssignmentExecutor:
         *,
         should_stop: Callable[[], bool] | None = None,
     ) -> AssignmentExecutionResult:
+        self._progress.clear()
         with bind_planner_execution_context(assignment):
             if should_stop is not None and should_stop():
                 return AssignmentExecutionResult(
@@ -50,6 +57,7 @@ class AssignmentExecutor:
     ) -> AssignmentExecutionResult:
         task = Task(goal=assignment.goal or "", device_id=assignment.device_id)
         runner = self.factories.task_runner_factory()
+        runner.on_step_progress = self._progress.update
         if should_stop is None:
             completed = runner.run(task)
         else: