feat: add weekly quality-report endpoint writing dated wiki report

POST /maintenance/quality-report {user}:
- runs the tenant-scoped duplicate scan (cosine >= threshold, default 0.9)
- flags stale pages: not updated in stale_days AND <= max_search_hits
  SearchQuery FOUND hits from the tenant's graph data
- lists pages missing tags/description (report subtree exempt)
- folds in the latest integrity-check results (Redis cache from
  /maintenance/integrity-check, or run inline when absent)
- writes the dated report to users/{user}/system/quality-reports/YYYY-MM-DD
  via the existing wiki write path; same-day reruns update the same page
  (page id remembered in Redis because the Wiki.js listing lags creation)
- response returns the full markdown report + page path + counts +
  duration_ms

Also fixes WikiJSClient.update_page: Wiki.js 2.x requires tags on the
update mutation (server maps over it unconditionally); calls without tags
failed with "Cannot read properties of undefined (reading 'map')" -
which also silently broke the consolidation page-update path. Current
tags are now preserved when the caller supplies none.

Verified live end-to-end on the local dev server as llm_tester
(tests/test_quality_report_live.py, integration-marked): probe page
flagged for missing metadata, report page written and fetched back,
same-day rerun updates in place, teardown leaves zero llm_tester pages.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QbFZyDvYksazX6nYQYZ67L

src/clients/wikijs_client.py

@@ -500,15 +500,21 @@ class WikiJSClient:
         }
         """
 
-        variables = {"id": page_id}
+        # Wiki.js 2.x requires `tags` on the update mutation (the server
+        # unconditionally maps over it; omitting it fails with "Cannot read
+        # properties of undefined (reading 'map')"). Preserve the page's
+        # current tags when the caller does not supply any.
+        if tags is None:
+            current = await self.get_page(page_id)
+            tags = (current or {}).get("tags") or []
+
+        variables = {"id": page_id, "tags": tags}
         if content is not None:
             variables["content"] = content
         if title is not None:
             variables["title"] = title
         if description is not None:
             variables["description"] = description
-        if tags is not None:
-            variables["tags"] = tags
         if is_published is not None:
             variables["isPublished"] = is_published