fix: reverte modelo para gemini-2.5-flash (cota gratuita maior) (#88)

gemini-2.5-flash tem 15 RPM e 1500 RPD no tier gratuito.
gemini-2.0-flash era desnecessário — o 2.5-flash está disponível
e tem melhor suporte a prompts complexos de DAX.

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

Author: vilpessoa

api/gemini.ts

@@ -47,7 +47,7 @@ export default async function handler(req: Request): Promise<Response> {
     });
   }
 
-  const model = body.model ?? 'gemini-2.0-flash';
+  const model = body.model ?? 'gemini-2.5-flash';
   const url = `https://generativelanguage.googleapis.com/v1beta/models/${model}:generateContent?key=${apiKey}`;
 
   const contents = [

src/services/geminiService.ts

@@ -59,7 +59,7 @@ export async function runAiAction(opts: RunAiActionOptions): Promise<string> {
         history: history ?? [],
         systemInstruction: promptText,
         actionContext: ACTION_CONTEXT[action],
-        model: 'gemini-2.0-flash',
+        model: 'gemini-2.5-flash',
       }),
       signal: controller.signal,
     });