feat: Add testimonials and update Gemini model

Integrates a testimonial system to display user results and feedback. This includes:
- Adding a new `testimonials` collection in Firestore.
- Implementing frontend components for displaying and submitting testimonials.
- Modifying the Gemini service to use the `gemini-3.1-pro-preview` model for enhanced analysis.
- Updating the `PlansView` with a new WhatsApp contact number.
- Enhancing the `AdminDashboard` to include testimonial creation capabilities.

src/services/geminiService.ts

@@ -4,7 +4,7 @@ import { AnalysisResponse, SignalType } from "../types";
 const ai = new GoogleGenAI({ apiKey: process.env.GEMINI_API_KEY || '' });
 
 export const analyzeForexChart = async (imageBase64: string, userNotes?: string, preferredMode?: 'Técnico' | 'Fundamental' | 'Híbrido'): Promise<AnalysisResponse> => {
-  const model = "gemini-3-flash-preview";
+  const model = "gemini-3.1-pro-preview";
   
   const systemInstruction = `
     Você é o QuantScan IA, um sistema avançado de análise de mercado financeiro com inteligência institucional.