fix(imap): address code review feedback on ingestion profiles

- Improve warning log in _resolve_categories_for_profile() to include
  exception type name for better troubleshooting
- Add SQLAlchemy IS NULL comment to imap_profiles.py filter
- Pass default_categories from server to template to avoid hardcoded
  category list in JS (now uses {{ default_categories | tojson }})
- Simplify view profiles query (remove redundant unauthenticated path)
- Update docs: ConfigurationGuide.md and EmailIngestion.md with
  full profiles documentation including category table and API reference

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/api/imap_profiles.py

@@ -154,6 +154,7 @@ def list_profiles(request: Request, db: DbSession, owner_id: CurrentOwner) -> li
     profiles = (
         db.query(ImapIngestionProfile)
         .filter(
+            # SQLAlchemy requires `== None` for IS NULL comparison in ORM filters
             (ImapIngestionProfile.owner_id == None) | (ImapIngestionProfile.owner_id == owner_id)  # noqa: E711
         )
         .order_by(ImapIngestionProfile.is_builtin.desc(), ImapIngestionProfile.id)