feat(provider.ollama): add chain-of-thought reasoning support to chat messages and Ollama provider

ts/abstract.classes.multimodal.ts

@@ -8,6 +8,8 @@ export interface ChatMessage {
   content: string;
   /** Base64-encoded images for vision-capable models */
   images?: string[];
+  /** Chain-of-thought reasoning for GPT-OSS models (e.g., Ollama) */
+  reasoning?: string;
 }
 
 /**
@@ -35,6 +37,8 @@ export interface StreamingChatOptions extends ChatOptions {
 export interface ChatResponse {
   role: 'assistant';
   message: string;
+  /** Chain-of-thought reasoning from reasoning models */
+  reasoning?: string;
 }
 
 /**