feat: focus priority, focus links, task list assignment, lists drag-and-drop, URL display fixes

- Focus page: turn sequence number into persistent editable priority (focus_priority column)
- Focus detail: add links section (add existing, create new, unlink) via focus_links junction table
- Focus detail: add copy and inline edit for checklist items
- Task detail lists tab: add existing list assignment and unlink actions
- Lists page: add drag-and-drop reorder support
- Links/bookmarks pages: remove artificial URL truncation, use CSS ellipsis

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

core/base_repository.py

@@ -162,7 +162,7 @@ class BaseRepository:
             "contact_id", "started_at",
             "weekly_hours", "effective_from",
             "task_id", "meeting_id", "list_item_id",
-            "domain_id", "title",
+            "domain_id", "title", "focus_priority",
         }
         clean_data = {}
         for k, v in data.items():