feat: add toggle to show unvalidated models in model selector (#413)

* feat: add toggle to show unvalidated models in model selector

Add a toggle switch in the model configuration dialog to allow users to
display models that haven't been validated. This helps users who work with
model providers that have disabled their verification endpoints.

Changes:
- Add showUnvalidatedModels field to MultiModelConfig type
- Add setShowUnvalidatedModels method to useModelConfig hook
- Add Switch toggle in model-config-dialog footer
- Update model-selector to filter based on showUnvalidatedModels setting
- Add warning icon for unvalidated models in the selector
- Add i18n translations for en/zh/ja

Closes #410

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix: wrap AlertTriangle in span for title attribute

The AlertTriangle icon from lucide-react doesn't support the title prop directly.
Wrapped it in a span element to properly display the tooltip.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

components/chat-input.tsx

@@ -162,6 +162,7 @@ interface ChatInputProps {
     models?: FlattenedModel[]
     selectedModelId?: string
     onModelSelect?: (modelId: string | undefined) => void
+    showUnvalidatedModels?: boolean
     onConfigureModels?: () => void
 }
 
@@ -183,6 +184,7 @@ export function ChatInput({
     models = [],
     selectedModelId,
     onModelSelect = () => {},
+    showUnvalidatedModels = false,
     onConfigureModels = () => {},
 }: ChatInputProps) {
     const dict = useDictionary()
@@ -482,6 +484,7 @@ export function ChatInput({
                             onSelect={onModelSelect}
                             onConfigure={onConfigureModels}
                             disabled={isDisabled}
+                            showUnvalidatedModels={showUnvalidatedModels}
                         />
 
                         <div className="w-px h-5 bg-border mx-1" />