fix(gateway): journal task_id auto-injection works from blocked/paused

Smoke-5 root cause. Agents wrote 5 decisions / 8 reflections / 1 struggle
during the run — every single entry persisted with task_id=NULL. The C8
tracing gate then never saw them and PMs spiraled forever on
'missing: journal:decision' while their decisions sat orphaned.

Cause: ContentActions.note/say/dm/notify called
TaskService.get_active_task_for_agent for task_id auto-injection. That
helper filters to _DEV_ACTIVE_STATUSES = {claimed, in_progress,
verifying, awaiting_qa, awaiting_documentation}. BLOCKED, PAUSED, and
NEEDS_REVISION fall outside that set — so the moment an agent gets
stuck (which is exactly when they journal), auto-injection returns None
and the entry persists without task_id.

Fix:
- New TaskService.get_journal_context_task_for_agent — same shape as
  get_active_task_for_agent but the status set
  _JOURNAL_CONTEXT_STATUSES adds BLOCKED, PAUSED, NEEDS_REVISION.
- ContentActions.note/say/dm/notify use the new lookup.
- ContentActions.commit keeps the narrow get_active_task_for_agent —
  can't commit from blocked, so the dev-active set is correct there.

Tests:
- tests/unit/services/test_journal_context_lookup.py — 5 tests pinning
  the two queries: journal-context INCLUDES blocked/paused/needs_revision,
  dev-active EXCLUDES them.
- Existing content-actions tests updated to stub the new method
  alongside the old one.

This alone may be 70% of what was killing smoke runs end-to-end.

tests/unit/gateway/test_notify.py

@@ -22,6 +22,7 @@ def _make_deps(**overrides: AsyncMock) -> ContentActionsDeps:
     else:
         task = AsyncMock()
         task.get_active_task_for_agent.return_value = None
+        task.get_journal_context_task_for_agent.return_value = None
         task.agent_for.return_value = MagicMock(role="cell_pm")
 
     git = overrides.get("git", AsyncMock())
@@ -239,6 +240,7 @@ async def test_notify_auto_fills_task_id_from_active_task() -> None:
     task_obj = MagicMock(id=task_id, status="awaiting_pm_review")
     task_svc = AsyncMock()
     task_svc.get_active_task_for_agent.return_value = task_obj
+    task_svc.get_journal_context_task_for_agent.return_value = task_obj
     task_svc.agent_for.return_value = MagicMock(role="cell_pm")
     notif_svc = AsyncMock()