feat: add multi-provider model configuration

- Add model config dialog for managing multiple AI providers
- Support for OpenAI, Anthropic, Google, Azure, Bedrock, OpenRouter, DeepSeek, SiliconFlow, Ollama, and AI Gateway
- Add model selector dropdown in chat panel header
- Add API key validation endpoint
- Add custom model ID input with keyboard navigation
- Fix hover highlight in Command component
- Add suggested models for each provider including latest Claude 4.5 series
- Store configuration locally in browser

lib/storage.ts

@@ -24,4 +24,8 @@ export const STORAGE_KEYS = {
     aiBaseUrl: "next-ai-draw-io-ai-base-url",
     aiApiKey: "next-ai-draw-io-ai-api-key",
     aiModel: "next-ai-draw-io-ai-model",
+
+    // Multi-model configuration
+    modelConfigs: "next-ai-draw-io-model-configs",
+    selectedModelId: "next-ai-draw-io-selected-model-id",
 } as const