fix: improve VLM validation with bug fixes and i18n

- Fix race condition in pendingValidationRef (reject previous pending validation)
- Fix response format consistency (use streaming for all responses)
- Remove dead code (unused lastRequestRef and ValidationRequest interface)
- Consolidate duplicate types (re-export from validation-schema.ts)
- Add 'success_with_warnings' status for valid diagrams with warnings
- Fix tool card auto-collapse (only collapse once, respect user toggle)
- Set VLM validation default to disabled
- Add i18n support for diagram validation settings (en/zh/ja)
- Mark feature as experimental in settings UI

components/chat/ToolCallCard.tsx

@@ -67,8 +67,8 @@ export function ToolCallCard({
 }: ToolCallCardProps) {
     const callId = part.toolCallId
     const { state, input, output } = part
-    // Default to collapsed if tool is complete, expanded if still streaming
-    const isExpanded = expandedTools[callId] ?? state !== "output-available"
+    // Default to expanded for all states (user can manually collapse if needed)
+    const isExpanded = expandedTools[callId] ?? true
     const toolName = part.type?.replace("tool-", "")
     const isCopied = copiedToolCallId === callId
 

components/chat/ValidationCard.tsx

@@ -19,6 +19,7 @@ export type ValidationStatus =
     | "capturing"
     | "validating"
     | "success"
+    | "success_with_warnings"
     | "failed"
     | "error"
     | "skipped"
@@ -95,7 +96,9 @@ export function ValidationCard({
     const showImproveButton =
         onImproveWithSuggestions &&
         state.result &&
-        (state.status === "success" || state.status === "skipped") &&
+        (state.status === "success" ||
+            state.status === "success_with_warnings" ||
+            state.status === "skipped") &&
         (state.result.issues.length > 0 || state.result.suggestions.length > 0)
 
     const getStatusDisplay = () => {
@@ -124,6 +127,14 @@ export function ValidationCard({
                     color: "text-green-600 bg-green-50",
                     icon: <Check className="h-4 w-4" aria-hidden="true" />,
                 }
+            case "success_with_warnings":
+                return {
+                    label: "Valid with Warnings",
+                    color: "text-amber-600 bg-amber-50",
+                    icon: (
+                        <AlertTriangle className="h-4 w-4" aria-hidden="true" />
+                    ),
+                }
             case "failed":
                 return {
                     label: "Issues Found",