fix: ruff findings

src/fenris/status_composition.py

@@ -11,25 +11,20 @@ Freshness grading uses shared constants from status.py.
 import enum
 import sqlite3
 from dataclasses import dataclass, field
-from datetime import datetime, timedelta, timezone
+from datetime import datetime, timezone
 from typing import Any, Dict, List, Optional
 
-# Status poll interval (AC78-6): lightweight 5s systemctl show poll
-STATUS_POLL_INTERVAL_S = 5
-
 from .status import (
-    FRESH_THRESHOLD_S,
-    STALENESS_THRESHOLD_S,
     grade_freshness,
     freshness_age_human,
     is_deliberately_paused,
     monitoring_continuity,
     deliberate_pause_lines,
-    open_store_readonly,
-    StoreFault,
-    NewerSchema,
 )
 
+# Status poll interval (AC78-6): lightweight 5s systemctl show poll
+STATUS_POLL_INTERVAL_S = 5
+
 
 # ---------------------------------------------------------------------------
 # Status state enum with glyph and label