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_tui_diagnostics.py

@@ -4,8 +4,7 @@ import sqlite3
 import pytest
 from test_dashboard_design import dashboard, visible  # noqa: F401  (fixtures)
 
-from fenris.activity_plot import VolumePoint
-from fenris.tui import FenrisTuiApp, HelpScreen, HistoryGraph
+from fenris.tui import FenrisTuiApp, HelpScreen
 
 
 def _store(app):
@@ -143,7 +142,6 @@ async def test_history_bars_draw_reads_alongside_writes_only_with_diagnostics(da
         await _settle(app, pilot)
         await pilot.press("v", "v")  # History
         await _settle(app, pilot)
-        graph = app.query_one(HistoryGraph)
         assert "Reads" not in _text(app, "#bar-legend")
         await pilot.press("i")
         await _settle(app, pilot)