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/management/AdminPanel.tsx

@@ -20,6 +20,7 @@ import {
   ChevronRight,
   HardDrive,
   Users,
+  Activity,
   Loader2,
 } from "lucide-react";
 import type { Tab, RoleInfo } from "@/types";
@@ -57,6 +58,18 @@ export function AdminPanel() {
           addTab(tab);
         }}
       />
+      <SessionsSection
+        connectionId={activeConnectionId}
+        onOpenSessions={() => {
+          const tab: Tab = {
+            id: crypto.randomUUID(),
+            type: "sessions",
+            title: "Active Sessions",
+            connectionId: activeConnectionId,
+          };
+          addTab(tab);
+        }}
+      />
     </div>
   );
 }
@@ -298,3 +311,34 @@ function RolesSection({
     </div>
   );
 }
+
+function SessionsSection({
+  connectionId,
+  onOpenSessions,
+}: {
+  connectionId: string;
+  onOpenSessions: () => void;
+}) {
+  return (
+    <div className="border-b">
+      <div className="flex items-center gap-1 px-3 py-2">
+        <Activity className="h-3.5 w-3.5 text-muted-foreground" />
+        <span className="text-xs font-semibold flex-1">Sessions</span>
+        <Button
+          variant="ghost"
+          size="sm"
+          className="h-5 px-1 text-[10px]"
+          onClick={onOpenSessions}
+          title="View active sessions"
+        >
+          View Sessions
+        </Button>
+      </div>
+      <div className="px-6 pb-2 text-xs text-muted-foreground">
+        Monitor active database connections and running queries.
+        {/* The connectionId is used by parent to open the sessions tab */}
+        <span className="hidden">{connectionId}</span>
+      </div>
+    </div>
+  );
+}