Update Gemini label to 3.1 in frontend model picker

Author: owenisas

frontend/src/lib/models.ts

@@ -4,7 +4,7 @@
 
 export const MODEL_OPTIONS = [
   { id: "gpt" as const, label: "GPT 5.2", enabled: true },
-  { id: "gemini" as const, label: "Gemini 2.5 Pro", enabled: true },
+  { id: "gemini" as const, label: "Gemini 3.1 Pro", enabled: true },
   { id: "claude" as const, label: "Claude Sonnet 4.6", enabled: false },
   { id: "polaris" as const, label: "Polaris Union", enabled: false },
   { id: "grok" as const, label: "Grok 4.1 Fast", enabled: false },