chore: prioritize gemini-3-pro over opus in oracle fallback chain

- Move gemini-3-pro above claude-opus-4-5 in oracle's fallbackChain
- Add variant: "max" to gemini-3-pro entry

src/shared/model-requirements.ts

@@ -21,8 +21,8 @@ export const AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
   oracle: {
     fallbackChain: [
       { providers: ["openai", "github-copilot", "opencode"], model: "gpt-5.2", variant: "high" },
+      { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro", variant: "max" },
       { providers: ["anthropic", "github-copilot", "opencode"], model: "claude-opus-4-5", variant: "max" },
-      { providers: ["google", "github-copilot", "opencode"], model: "gemini-3-pro" },
     ],
   },
    librarian: {