fix(installer): add opencode-go fallback entries for deep and artistry categories

The deep and artistry category fallback chains had no opencode-go provider
entries, causing them to fall through to the ultimate fallback
(opencode/gpt-5-nano) which is not available to opencode-go users.

Add opencode-go entries:
- deep: deepseek-v4-pro -> kimi-k2.6 -> glm-5.1
- artistry: kimi-k2.6 -> glm-5.1

Fixes #3924

src/shared/model-requirements.ts

@@ -244,6 +244,8 @@ export const CATEGORY_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
         model: "gemini-3.1-pro",
         variant: "high",
       },
+      { providers: ["opencode-go", "vercel"], model: "kimi-k2.6" },
+      { providers: ["opencode-go", "vercel"], model: "glm-5.1" },
     ],
   },
   artistry: {
@@ -259,6 +261,8 @@ export const CATEGORY_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
         variant: "max",
       },
       { providers: ["openai", "github-copilot", "opencode", "vercel"], model: "gpt-5.5" },
+      { providers: ["opencode-go", "vercel"], model: "kimi-k2.6" },
+      { providers: ["opencode-go", "vercel"], model: "glm-5.1" },
     ],
   },
   quick: {