feat(settings): Settings → System shows table sizes and what the last cleanup removed (#5469)

#5469 "Settings → System: table sizes and what the last cleanup removed".

- Storage: each table's size on disk (pg_total_relation_size, indexes and TOAST
  included) and Postgres's row estimate (reltuples), largest first, the 15
  largest by name and the rest summed, under the database's total size. Read
  from the catalog only, never by counting rows.
- Last cleanup: when it ran, how long it took, and what each pass removed (each
  aged table, run log files, the metric and Docker rollups, the log ring), or
  "Nothing was past its window". run_cleanup now returns that summary and keeps
  it as the cleanup.last_run setting, as reports.last_sent_at does; cleanup_secs
  (#5467) is recorded from the same figure.
- A hint links to where each retention window is set.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/integration/test_cleanup.py

@@ -22,7 +22,7 @@ def app():
 def test_the_audit_window_comes_from_settings(app):
     from sqlalchemy import text
     from steward.core.cleanup import run_cleanup
-    from steward.core.settings import set_setting
+    from steward.core.settings import get_setting, set_setting
     from steward.models.audit import AuditEvent
 
     now = datetime.now(timezone.utc)
@@ -35,16 +35,23 @@ def test_the_audit_window_comes_from_settings(app):
                 s.add(AuditEvent(action=tag, entity_id="old", timestamp=now - timedelta(days=40)))
                 s.add(AuditEvent(action=tag, entity_id="new", timestamp=now - timedelta(days=20)))
         try:
-            await run_cleanup(app)
+            done = await run_cleanup(app)
         finally:
             async with app.db_sessionmaker() as s:
                 async with s.begin():
                     await set_setting(s, "audit.retention_days", 365)
         async with app.db_sessionmaker() as s:
-            return [r[0] for r in (await s.execute(text(
+            kept = [r[0] for r in (await s.execute(text(
                 "SELECT entity_id FROM audit_events WHERE action = :a"), {"a": tag})).all()]
+            return kept, done, await get_setting(s, "cleanup.last_run")
 
-    assert asyncio.run(_go()) == ["new"]
+    kept, done, stored = asyncio.run(_go())
+    assert kept == ["new"]
+    # What it did is kept for Settings → System (#5469), each pass by name.
+    counts = dict(done["removed"])
+    assert counts["audit_events: older than 30 days"] >= 1
+    assert "plugin_metrics: raw samples rolled into hourly" in counts and done["secs"] >= 0
+    assert stored == done
 
 
 def test_the_chart_seam_follows_the_raw_metrics_setting(app):
@@ -77,3 +84,19 @@ def test_the_chart_seam_follows_the_raw_metrics_setting(app):
                     await set_setting(s, "metrics.retention.raw_days", 7)
 
     assert [v for _, v in asyncio.run(_go())] == [10.0]
+
+
+def test_table_sizes_come_from_the_catalog_largest_first(app):
+    """Settings → System's storage figures (#5469), read against real Postgres."""
+    from steward.core.health import TABLES_SHOWN, table_sizes
+
+    async def _go():
+        async with app.db_sessionmaker() as s:
+            return await table_sizes(s)
+
+    got = asyncio.run(_go())
+    sizes = [t["bytes"] for t in got["tables"]]
+    assert sizes == sorted(sizes, reverse=True) and len(sizes) <= TABLES_SHOWN
+    names = {t["name"] for t in got["tables"]}
+    assert got["rest"]["count"] or "audit_events" in names       # the schema's own tables
+    assert got["total"] >= sum(sizes) + got["rest"]["bytes"] > 0