Merge origin/main into main

Reconcile the staged-projection and Diagnostics feature work with the CI
quality-gate changes from origin/main. The origin side of every conflict was
lint-only, so the feature imports were kept and the ruff fixes re-applied:

- keep the branch's added imports (timefmt, activity_readout, projection
  ladder helpers) and drop the unused ones ruff reported
- restore `noqa: E402` on the post-bootstrap imports in fenris-monitor and
  keep the `noqa: F401` re-exports in the TUI that tests assert on
- make the TUI monitoring-glyph test clock-relative instead of pinned to a
  fixed date

tests/test_acceptance_sweep.py

@@ -9,7 +9,6 @@ CI-3  Prohibition set: automated structural checks
 CI-4  Required wording and six disclosures in both views
 """
 import re
-import sqlite3
 from datetime import datetime, timedelta, timezone
 from pathlib import Path
 from unittest.mock import patch
@@ -19,16 +18,13 @@ import sys
 
 sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
 
-from fenris.store import init_store, SCHEMA_VERSION
+from fenris.store import init_store
 from fenris.monitoring_periods import ensure_period_open
 from fenris.projection import (
     compute_projection,
     ConfidenceState,
     BaselineTier,
     DISCLOSURES,
-    STALENESS_HOURS,
-    WARMING_MIN_DAYS,
-    YOUNG_REGIME_DAYS,
 )
 from fenris.status import (
     grade_freshness,
@@ -36,13 +32,9 @@ from fenris.status import (
     render_status,
     format_disclosures,
     FRESH_THRESHOLD_S,
-    STALENESS_THRESHOLD_S,
-    CADENCE_DEFAULT_S,
-    ACCURACY_SEC,
 )
 from fenris.tui import (
     FenrisTuiApp,
-    _format_remaining,
 )