feat(docker): container log viewer + Settings controls [M79 step 5]

The user-facing half (rule 27). Per-container log viewer + admin controls, so
container logs are something the operator can actually touch.

Viewer (plugins/docker):
- /container/<host>/<name>/logs full page + /logs/lines HTMX fragment polled
  every 5s (near-live follow); stream filter (all/stdout/stderr) + case-insensitive
  text search; newest-first so the latest lines survive the poll's scroll reset;
  empty/loading states; a "View logs" link from the container detail page.
  Jinja auto-escapes log content (no markup injection).

Settings (Thresholds & Retention tab):
- global on/off toggle, comma-separated exclude list, retention days + max MB
  per container — DB-backed, no restart. The toggle + exclude are enforced
  authoritatively at ingest (_persist_logs drops disabled/excluded lines), since
  the push model has no channel to tell an agent to stop.

Tests: route-defined smoke; template-parse covers the new templates; integration
test for the ingest-time toggle + exclude enforcement.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CAGR73DUowdVFVvYzLXC5C

tests/integration/test_docker.py

@@ -210,6 +210,50 @@ def test_persist_logs_stores_lines(app):
     ]
 
 
+@_NEEDS_DB
+def test_persist_logs_respects_toggle_and_exclude(app):
+    """Server-side controls (Settings): an excluded container's lines are dropped
+    while others persist; the global toggle off stores nothing new."""
+    from sqlalchemy import text
+    from steward.models.hosts import Host
+    from steward.core.settings import set_setting
+
+    persist = _persist_fn(app)
+    now = datetime.now(timezone.utc)
+    batch = [(now, [
+        {"container": "web", "stream": "stdout", "ts": None, "line": "keep-me"},
+        {"container": "noisy", "stream": "stdout", "ts": None, "line": "drop-me"},
+    ])]
+
+    async def _go():
+        async with app.db_sessionmaker() as s:
+            async with s.begin():
+                await s.execute(text("DELETE FROM docker_logs"))
+                await set_setting(s, "docker.logs.enabled", True)
+                await set_setting(s, "docker.logs.exclude", ["noisy"])
+                h = Host(id=str(uuid.uuid4()), name="loghost3", address="10.7.7.10")
+                s.add(h)
+                await s.flush()
+                hid = h.id
+                await persist(s, h, [], None, None, batch)
+            kept = {r[0] for r in (await s.execute(text(
+                "SELECT DISTINCT container_name FROM docker_logs WHERE host_id=:h"),
+                {"h": hid})).all()}
+            async with s.begin():          # flip the global kill-switch off
+                await set_setting(s, "docker.logs.enabled", False)
+                await persist(s, h, [], None, None, batch)
+            after_off = (await s.execute(text(
+                "SELECT COUNT(*) FROM docker_logs WHERE host_id=:h"), {"h": hid})).scalar()
+            async with s.begin():          # restore defaults for other tests
+                await set_setting(s, "docker.logs.enabled", True)
+                await set_setting(s, "docker.logs.exclude", [])
+            return kept, after_off
+
+    kept, after_off = asyncio.run(_go())
+    assert kept == {"web"}      # excluded 'noisy' dropped on ingest
+    assert after_off == 1       # toggle off → no new rows (still just the one 'web')
+
+
 @_NEEDS_DB
 def test_large_memory_values_persist_as_bigint(app):
     """A container using >2^31 bytes of RAM must persist. Regression: mem_usage_bytes

tests/plugins/docker/test_routes.py

@@ -35,6 +35,12 @@ def test_disk_prune_view_defined():
     assert callable(r.disk_prune)
 
 
+def test_container_log_views_defined():
+    # M79 per-container log viewer + its HTMX-polled line fragment.
+    assert callable(r.container_logs)
+    assert callable(r.container_logs_lines)
+
+
 def test_prune_extra_vars_mapping():
     """The prune buttons drive one playbook via prune_target; only 'images'
     widens to ALL unused images (docker image prune -a), system stays -f."""