feat(presets): add Unity2.ai partner provider across seven apps

Add Unity2.ai, a high-performance AI API relay partner, as a preset for
Claude, Codex, Gemini, OpenCode, OpenClaw, Claude Desktop, and Hermes.
Each preset carries the referral signup link as apiKeyUrl.

- Register the unity2 icon via iconUrls (PNG URL import) + metadata
- Add partnerPromotion copy in zh/en/ja/zh-TW; backfill the missing
  zh-TW ccsub entry
- List Unity2.ai in the sponsor section of all README locales
- Codex uses the bare base URL (gateway exposes /responses at root);
  OpenCode/OpenClaw/Hermes use the /v1 chat-completions endpoint with
  gpt-5.5 as the only preset model
- Trim CCSub OpenCode/OpenClaw/Hermes model lists to gpt-5.5 to match
- Normalize unity2/ccsub banners to the standard 2.41 aspect ratio

src/config/codexProviderPresets.ts

@@ -231,6 +231,22 @@ export const codexProviderPresets: CodexProviderPreset[] = [
     partnerPromotionKey: "ccsub",
     icon: "ccsub",
   },
+  {
+    name: "Unity2.ai",
+    websiteUrl: "https://unity2.ai",
+    apiKeyUrl: "https://unity2.ai/register?source=ccs",
+    category: "aggregator",
+    auth: generateThirdPartyAuth(""),
+    config: generateThirdPartyConfig(
+      "unity2",
+      "https://api.unity2.ai",
+      "gpt-5.5",
+    ),
+    endpointCandidates: ["https://api.unity2.ai"],
+    isPartner: true,
+    partnerPromotionKey: "unity2",
+    icon: "unity2",
+  },
   {
     name: "Azure OpenAI",
     websiteUrl: