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/components/ai/AiBar.tsx

@@ -0,0 +1,92 @@
+import { useState } from "react";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { AiSettingsPopover } from "./AiSettingsPopover";
+import { useGenerateSql } from "@/hooks/use-ai";
+import { Sparkles, Loader2, X } from "lucide-react";
+import { toast } from "sonner";
+
+interface Props {
+  connectionId: string;
+  onSqlGenerated: (sql: string) => void;
+  onClose: () => void;
+  onExecute?: () => void;
+}
+
+export function AiBar({ connectionId, onSqlGenerated, onClose, onExecute }: Props) {
+  const [prompt, setPrompt] = useState("");
+  const generateMutation = useGenerateSql();
+
+  const handleGenerate = () => {
+    if (!prompt.trim() || generateMutation.isPending) return;
+    generateMutation.mutate(
+      { connectionId, prompt },
+      {
+        onSuccess: (sql) => {
+          onSqlGenerated(sql);
+          setPrompt("");
+        },
+        onError: (err) => {
+          toast.error("AI generation failed", { description: String(err) });
+        },
+      }
+    );
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent) => {
+    if (e.key === "Enter" && (e.ctrlKey || e.metaKey)) {
+      e.preventDefault();
+      e.stopPropagation();
+      onExecute?.();
+      return;
+    }
+    if (e.key === "Enter" && !e.shiftKey) {
+      e.preventDefault();
+      e.stopPropagation();
+      handleGenerate();
+      return;
+    }
+    if (e.key === "Escape") {
+      e.stopPropagation();
+      onClose();
+    }
+  };
+
+  return (
+    <div className="flex items-center gap-2 border-b bg-muted/50 px-2 py-1">
+      <Sparkles className="h-3.5 w-3.5 shrink-0 text-purple-500" />
+      <Input
+        value={prompt}
+        onChange={(e) => setPrompt(e.target.value)}
+        onKeyDown={handleKeyDown}
+        placeholder="Describe the query you want..."
+        className="h-7 min-w-0 flex-1 text-xs"
+        autoFocus
+        disabled={generateMutation.isPending}
+      />
+      <Button
+        size="sm"
+        variant="ghost"
+        className="h-6 gap-1 text-xs"
+        onClick={handleGenerate}
+        disabled={generateMutation.isPending || !prompt.trim()}
+      >
+        {generateMutation.isPending ? (
+          <Loader2 className="h-3 w-3 animate-spin" />
+        ) : (
+          "Generate"
+        )}
+      </Button>
+      <AiSettingsPopover />
+      <Button
+        size="sm"
+        variant="ghost"
+        className="h-6 w-6 p-0"
+        onClick={onClose}
+        title="Close AI bar"
+      >
+        <X className="h-3 w-3" />
+      </Button>
+    </div>
+  );
+}