fix(ai): correct Gemini SDK payload property thinkingBudgetTokens to thinkingBudget

vibn-frontend/lib/ai/gemini-chat.ts

@@ -114,7 +114,7 @@ export async function callGeminiChat(opts: {
     }
 
     if (opts.includeThoughts) {
-        config.thinkingConfig = { thinkingBudgetTokens: 1024 };
+        config.thinkingConfig = { thinkingBudget: 1024 };
     }
 
     const fns = toGeminiFunctions(opts.tools ?? []);
@@ -174,7 +174,7 @@ export async function* streamGeminiChat(opts: {
     const config: any = {
       temperature: opts.temperature ?? 0.7,
       maxOutputTokens: 8192,
-      thinkingConfig: { thinkingBudgetTokens: 1024 },
+      thinkingConfig: { thinkingBudget: 1024 },
     };
 
     if (opts.systemPrompt) {

vibn-frontend/lib/ai/gemini-client.ts

@@ -88,7 +88,7 @@ export class GeminiLlmClient implements LlmClient {
 
     if (args.thinking_config) {
       config.thinkingConfig = {
-        thinkingBudgetTokens: 1024,
+        thinkingBudget: 1024,
       };
     }