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>

openspec/changes/task-execution-progress-visibility/specs/cloud-task-progress-visibility/spec.md

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+## ADDED Requirements
+
+### Requirement: Cloud Control Plane exposes the latest in-progress step status for an active assignment
+The Cloud Control Plane's existing task query surface SHALL include the latest reported step index, step status, and summary for any assignment that has an in-progress Host Agent execution, alongside the task's existing status fields.
+
+#### Scenario: An assignment has reported progress
+- **WHEN** an operator queries a task that has an active, in-progress assignment with previously reported step progress
+- **THEN** the response includes that step's index, status, and summary alongside the task's existing fields
+
+#### Scenario: An assignment has no reported progress yet
+- **WHEN** an operator queries a task whose active assignment has not yet reported any progress
+- **THEN** the response omits progress fields rather than showing stale or default values
+
+#### Scenario: An assignment has reached a terminal state
+- **WHEN** an operator queries a task whose assignment has already completed (succeeded or failed)
+- **THEN** the response does not present the last in-progress step as current status; the task's terminal status and result take precedence
+
+### Requirement: Cloud Console renders live step progress for in-progress tasks
+Cloud Console SHALL display the current step index, status, and summary for a task with an active, in-progress Host Agent execution, refreshed on its existing polling interval, without requiring a new push channel.
+
+#### Scenario: Operator views an in-progress task
+- **WHEN** an operator opens a task detail view for a task with an active in-progress assignment
+- **THEN** Cloud Console shows the latest known step index, status, and summary, updating on subsequent polls as new progress is reported
+
+#### Scenario: Operator views a task with no in-progress execution
+- **WHEN** an operator opens a task detail view for a queued, terminal, or otherwise not-currently-executing task
+- **THEN** Cloud Console does not display stale in-progress step information
+
+### Requirement: Cloud Console displays a task's full LLM interaction history
+Cloud Console SHALL provide a view, for a given task, listing each persisted planner decision in step order, including its full prompt and resulting decision, sourced from the Cloud Control Plane's persisted planner decision log.
+
+#### Scenario: Task has persisted planner decisions
+- **WHEN** an operator opens the LLM interaction history view for a task that has one or more persisted planner decisions
+- **THEN** Cloud Console shows each decision in step order with its prompt and resulting tool call
+
+#### Scenario: Task's host used the direct-to-provider transport
+- **WHEN** an operator opens the LLM interaction history view for a task whose host used the direct-to-provider transport
+- **THEN** Cloud Console indicates that no LLM interaction history is available because the host does not report it, rather than showing an empty history with no explanation