refactor(tui): extract Activity readout and show local time

Move activity data assembly out of tui.py into activity_readout, behind
readout(conn, selection, now). Dashboard and fenris-monitor enable now show
local time with a timezone label, inspected points keep a secondary UTC line,
and the legacy UTC-relabelled day and hour branches are gone. Time formatting
(including freshness_age_human) lives in timefmt. Hour offsets now render as
+05:30 to match day labels.

tests/test_tui.py

@@ -38,13 +38,15 @@ from fenris.status import (
     STALENESS_THRESHOLD_S,
     grade_freshness,
 )
+from fenris.activity_readout import (
+    _query_daily_graph_data,
+    _query_drive_health,
+    _query_hourly_graph_data,
+)
 from fenris.tui import (
     FenrisTuiApp,
     HistoryGraph,
     _format_remaining,
-    _query_drive_health,
-    _query_daily_graph_data,
-    _query_hourly_graph_data,
     _RANGE_OPTIONS,
     _RANGE_DEFAULT,
     _MIN_WIDTH,