refactor(ai): consolidate AI around chat tool-calling; add OpenRouter

- rework chat backend (chat.rs, chat_tools.rs, ai.rs, models, state) around tool calls
- add OpenRouter provider alongside Ollama/Fireworks in settings
- drop inline AiBar, ResultsPanel explain/fix UI and ChartPreview in favour of the chat panel
- add frontend chat tool-registry

src/components/workspace/WorkspacePanel.tsx

@@ -13,7 +13,7 @@ import { useCompletionSchema } from "@/hooks/use-completion-schema";
 import { useConnections } from "@/hooks/use-connections";
 import { useAppStore } from "@/stores/app-store";
 import { Button } from "@/components/ui/button";
-import { Play, Loader2, Lock, BarChart3, Download, AlignLeft, Bookmark, Table2, Braces, Sparkles, BrainCircuit } from "lucide-react";
+import { Play, Loader2, Lock, BarChart3, Download, AlignLeft, Bookmark, Table2, Braces } from "lucide-react";
 import { format as formatSql } from "sql-formatter";
 import { SaveQueryDialog } from "@/components/saved-queries/SaveQueryDialog";
 import {
@@ -25,8 +25,6 @@ import {
 import { exportCsv, exportJson } from "@/lib/tauri";
 import { save } from "@tauri-apps/plugin-dialog";
 import { toast } from "sonner";
-import { AiBar } from "@/components/ai/AiBar";
-import { useExplainSql, useFixSqlError } from "@/hooks/use-ai";
 import type { QueryResult, ExplainResult } from "@/types";
 
 interface Props {
@@ -53,12 +51,8 @@ export function WorkspacePanel({
   const [resultView, setResultView] = useState<"results" | "explain">("results");
   const [resultViewMode, setResultViewMode] = useState<"table" | "json">("table");
   const [saveDialogOpen, setSaveDialogOpen] = useState(false);
-  const [aiBarOpen, setAiBarOpen] = useState(false);
-  const [aiExplanation, setAiExplanation] = useState<string | null>(null);
 
   const queryMutation = useQueryExecution();
-  const explainMutation = useExplainSql();
-  const fixMutation = useFixSqlError();
   const addHistoryMutation = useAddHistory();
   const { data: connections } = useConnections();
   const { data: completionSchema } = useCompletionSchema(connectionId);
@@ -102,7 +96,6 @@ export function WorkspacePanel({
     if (!sqlValue.trim() || !connectionId) return;
     setError(null);
     setExplainData(null);
-    setAiExplanation(null);
     setResultView("results");
     queryMutation.mutate(
       { connectionId, sql: sqlValue },
@@ -196,60 +189,6 @@ export function WorkspacePanel({
     [result]
   );
 
-  const isAiLoading = explainMutation.isPending || fixMutation.isPending;
-
-  const handleAiExplain = useCallback(() => {
-    if (!sqlValue.trim() || !connectionId) return;
-    setAiExplanation(null);
-    setResultView("results");
-    explainMutation.mutate(
-      { connectionId, sql: sqlValue },
-      {
-        onSuccess: (explanation) => {
-          setAiExplanation(explanation);
-        },
-        onError: (err) => {
-          toast.error("AI Explain failed", { description: String(err) });
-        },
-      }
-    );
-  }, [connectionId, sqlValue, explainMutation]);
-
-  const handleExplainError = useCallback(() => {
-    if (!sqlValue.trim() || !connectionId || !error) return;
-    setAiExplanation(null);
-    explainMutation.mutate(
-      { connectionId, sql: `${sqlValue}\n\n-- Error: ${error}` },
-      {
-        onSuccess: (explanation) => {
-          setAiExplanation(explanation);
-        },
-        onError: (err) => {
-          toast.error("AI Explain failed", { description: String(err) });
-        },
-      }
-    );
-  }, [connectionId, sqlValue, error, explainMutation]);
-
-  const handleFixError = useCallback(() => {
-    if (!sqlValue.trim() || !connectionId || !error) return;
-    fixMutation.mutate(
-      { connectionId, sql: sqlValue, errorMessage: error },
-      {
-        onSuccess: (fixedSql) => {
-          setSqlValue(fixedSql);
-          onSqlChange?.(fixedSql);
-          setError(null);
-          setAiExplanation(null);
-          toast.success("SQL replaced by AI suggestion");
-        },
-        onError: (err) => {
-          toast.error("AI Fix failed", { description: String(err) });
-        },
-      }
-    );
-  }, [connectionId, sqlValue, error, fixMutation, onSqlChange]);
-
   return (
     <>
     <ResizablePanelGroup orientation="vertical">
@@ -308,35 +247,6 @@ export function WorkspacePanel({
               Save
             </Button>
 
-            <div className="mx-1 h-3.5 w-px bg-border/40" />
-
-            {/* AI actions group — purple-branded */}
-            <Button
-              size="xs"
-              variant={aiBarOpen ? "secondary" : "ghost"}
-              className={`gap-1 text-[11px] ${aiBarOpen ? "text-tusk-purple" : ""}`}
-              onClick={() => setAiBarOpen(!aiBarOpen)}
-              title="AI SQL Generator"
-            >
-              <Sparkles className={`h-3 w-3 ${aiBarOpen ? "tusk-ai-icon" : ""}`} />
-              AI
-            </Button>
-            <Button
-              size="xs"
-              variant="ghost"
-              className="gap-1 text-[11px]"
-              onClick={handleAiExplain}
-              disabled={isAiLoading || !sqlValue.trim()}
-              title="Explain query with AI"
-            >
-              {isAiLoading ? (
-                <Loader2 className="h-3 w-3 animate-spin" />
-              ) : (
-                <BrainCircuit className="h-3 w-3" />
-              )}
-              AI Explain
-            </Button>
-
             {result && result.columns.length > 0 && (
               <>
                 <div className="mx-1 h-3.5 w-px bg-border/40" />
@@ -369,23 +279,12 @@ export function WorkspacePanel({
               {"\u2318"}Enter
             </span>
             {isReadOnly && (
-              <span className="ml-2 flex items-center gap-1 rounded-sm bg-amber-500/10 px-1.5 py-0.5 text-[10px] font-semibold tracking-wide text-amber-500">
+              <span className="ml-2 flex items-center gap-1 rounded-sm bg-warning/10 px-1.5 py-0.5 text-[10px] font-semibold tracking-wide text-warning">
                 <Lock className="h-2.5 w-2.5" />
                 READ
               </span>
             )}
           </div>
-          {aiBarOpen && (
-            <AiBar
-              connectionId={connectionId}
-              onSqlGenerated={(sql) => {
-                setSqlValue(sql);
-                onSqlChange?.(sql);
-              }}
-              onClose={() => setAiBarOpen(false)}
-              onExecute={handleExecute}
-            />
-          )}
           <div className="min-h-0 flex-1">
             <SqlEditor
               value={sqlValue}
@@ -400,7 +299,7 @@ export function WorkspacePanel({
       <ResizableHandle withHandle />
       <ResizablePanel id="results" defaultSize="60%" minSize="15%">
         <div className="flex h-full flex-col overflow-hidden">
-          {(explainData || result || error || aiExplanation) && (
+          {(explainData || result || error) && (
             <div className="flex shrink-0 items-center border-b border-border/40 text-xs">
               <button
                 className={`relative px-3 py-1.5 font-medium transition-colors ${
@@ -469,10 +368,6 @@ export function WorkspacePanel({
                 error={error}
                 isLoading={queryMutation.isPending && resultView === "results"}
                 viewMode={resultViewMode}
-                aiExplanation={aiExplanation}
-                isAiLoading={isAiLoading}
-                onExplainError={error ? handleExplainError : undefined}
-                onFixError={error ? handleFixError : undefined}
               />
             )}
           </div>