feat: add column sort, SQL formatter, table stats, insert dialog, saved queries & sessions monitor

- Column sort by header click in table view (ASC/DESC/none cycle, server-side)
- SQL formatter with Format button and Shift+Alt+F keybinding (sql-formatter)
- Table size and row count display in schema tree via pg_class
- Insert row dialog with column type hints and auto-skip for identity columns
- Saved queries (bookmarks) with CRUD backend, sidebar panel, and save dialog
- Active sessions monitor (pg_stat_activity) with auto-refresh, cancel & terminate

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

package.json

@@ -29,6 +29,7 @@
     "react-dom": "^19.2.0",
     "react-resizable-panels": "^4.6.2",
     "sonner": "^2.0.7",
+    "sql-formatter": "^15.7.0",
     "tailwind-merge": "^3.4.0",
     "zustand": "^5.0.11"
   },