feat: add Greenplum 7 compatibility and AI SQL generation

Greenplum 7 (PG12-based) compatibility:
- Auto-detect GP via version() string, store DbFlavor per connection
- connect returns ConnectResult with version + flavor
- Fix pg_total_relation_size to use c.oid (universal, safer on both PG/GP)
- Branch is_identity column query for GP (lacks the column)
- Branch list_sessions wait_event fields for GP
- Exclude gp_toolkit schema in schema listing, completion, lookup, AI context
- Smart StatusBar version display: GP shows "GP 7.0.0 (PG 12.4)"
- Fix connection list spinner showing on all cards during connect

AI SQL generation (Ollama):
- Add AI settings, model selection, and generate_sql command
- Frontend AI panel with prompt input and SQL output

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

src/App.tsx

@@ -13,7 +13,7 @@ import { useAppStore } from "@/stores/app-store";
 import type { Tab } from "@/types";
 
 export default function App() {
-  const { activeConnectionId, addTab } = useAppStore();
+  const { activeConnectionId, currentDatabase, addTab } = useAppStore();
 
   const handleNewQuery = useCallback(() => {
     if (!activeConnectionId) return;
@@ -22,10 +22,11 @@ export default function App() {
       type: "query",
       title: "New Query",
       connectionId: activeConnectionId,
+      database: currentDatabase ?? undefined,
       sql: "",
     };
     addTab(tab);
-  }, [activeConnectionId, addTab]);
+  }, [activeConnectionId, currentDatabase, addTab]);
 
   const handleCloseTab = useCallback(() => {
     const { activeTabId, closeTab } = useAppStore.getState();