fix: ruff findings

tests/test_measured_activity.py

@@ -21,9 +21,7 @@ import sys
 sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
 
 from fenris.collector import run_collection
-from fenris.store import init_store
 from fenris.day_aggregate import derive_day
-from fenris.monitoring_periods import ensure_period_open
 from fenris.tui import _query_daily_graph_data, _query_hourly_graph_data
 
 
@@ -247,7 +245,6 @@ class TestCrossHourAttribution:
         for day in ("2026-09-01",):
             agg = derive_day(conn, day)
             assert agg is not None
-            total_accounted = agg.bytes_written_delta + agg.bytes_read_delta
             unattributed_w = conn.execute(
                 "SELECT unattributed_bytes_written FROM day_aggregates WHERE day = ?",
                 (day,)
@@ -483,7 +480,6 @@ class TestCrossDayBoundary:
 
         # The cross-day delta is unattributed at the day level
         sep1 = day_map["2026-09-01"]
-        sep2 = day_map["2026-09-02"]
         # Both days may show the unattributed bytes
         # (the delta is added to both days' unattributed totals as evidence)
         total_w = sep1["allocated_bytes"] + sep1["unallocated_bytes"]