fix(clustering): drop TTL check from isUpToDate; task hash is the only signal

If tasks haven't changed, the output is valid forever. If they changed,
always recompute regardless of age. TTL on focus-area restored to 24h —
it only controls recommender eligibility, not recompute frequency.

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

ml/agents/focus_area.py

@@ -37,7 +37,7 @@ MANIFEST = AgentManifest(
     context_schema=["todoist.tasks"],
     required_consents=["data:core", "data:todoist"],
     output_contract={"type": "snippet", "format": "free_text"},
-    ttl_sec=3_600,
+    ttl_sec=86_400,
     inferred_params=[
         InferredParam(
             key="preferred_areas",