fix: .env.example default COACH_PROVIDER to perplexity

.env.example

@@ -12,7 +12,7 @@ PPLX_API_KEY=your-perplexity-api-key-here
 # Perplexity model for deck research & generation (sonar / sonar-pro / sonar-deep-research)
 PPLX_MODEL=sonar-pro
 # Coach chat provider: "local" (Ollama) or "perplexity" (Perplexity API)
-COACH_PROVIDER=local
+COACH_PROVIDER=perplexity
 
 # CORS allowed origins (comma-separated)
 # Default: http://localhost:5173,http://localhost:8080