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>

src/components/workspace/TabContent.tsx

@@ -3,6 +3,7 @@ import { WorkspacePanel } from "./WorkspacePanel";
 import { TableDataView } from "@/components/table-viewer/TableDataView";
 import { TableStructure } from "@/components/table-viewer/TableStructure";
 import { RoleManagerView } from "@/components/management/RoleManagerView";
+import { SessionsView } from "@/components/management/SessionsView";
 
 export function TabContent() {
   const { tabs, activeTabId, updateTab } = useAppStore();
@@ -51,6 +52,13 @@ export function TabContent() {
           connectionId={activeTab.connectionId}
         />
       );
+    case "sessions":
+      return (
+        <SessionsView
+          key={activeTab.id}
+          connectionId={activeTab.connectionId}
+        />
+      );
     default:
       return null;
   }