refine(ui): improve model placeholders and simplify provider hints

- Add dedicated Haiku model placeholder "GLM-4.5-Air"
- Unify API key hints for all non-official providers
- Fix AiHubMix category from cn_official to aggregator
- Standardize GLM model name format (glm-4.6)

src/config/codexProviderPresets.ts

@@ -73,7 +73,7 @@ export const codexProviderPresets: CodexProviderPreset[] = [
   {
     name: "AiHubMix",
     websiteUrl: "https://aihubmix.com",
-    category: "cn_official",
+    category: "aggregator",
     auth: generateThirdPartyAuth(""),
     config: generateThirdPartyConfig(
       "aihubmix",