feat: add AI data validation, test data generator, index advisor, and snapshots

Four new killer features leveraging AI (Ollama) and PostgreSQL internals:

- Data Validation: describe quality rules in natural language, AI generates
  SQL to find violations, run with pass/fail results and sample violations
- Test Data Generator: right-click table to generate realistic FK-aware test
  data with AI, preview before inserting in a transaction
- Index Advisor: analyze pg_stat tables + AI recommendations for CREATE/DROP
  INDEX with one-click apply
- Data Snapshots: export selected tables to JSON (FK-ordered), restore from
  file with optional truncate in a transaction

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

src/components/layout/TabBar.tsx

@@ -1,7 +1,7 @@
 import { useAppStore } from "@/stores/app-store";
 import { useConnections } from "@/hooks/use-connections";
 import { ScrollArea } from "@/components/ui/scroll-area";
-import { X, Table2, Code, Columns, Users, Activity, Search, GitFork } from "lucide-react";
+import { X, Table2, Code, Columns, Users, Activity, Search, GitFork, ShieldCheck, Gauge, Camera } from "lucide-react";
 
 export function TabBar() {
   const { tabs, activeTabId, setActiveTabId, closeTab } = useAppStore();
@@ -17,6 +17,9 @@ export function TabBar() {
     sessions: <Activity className="h-3 w-3" />,
     lookup: <Search className="h-3 w-3" />,
     erd: <GitFork className="h-3 w-3" />,
+    validation: <ShieldCheck className="h-3 w-3" />,
+    "index-advisor": <Gauge className="h-3 w-3" />,
+    snapshots: <Camera className="h-3 w-3" />,
   };
 
   return (