feat(presets): add Code0.ai partner preset for 7 apps

Partner aggregator (New API gateway) across Claude Code, Claude Desktop,
Codex, Gemini, OpenCode, OpenClaw, and Hermes. Claude Code, Claude
Desktop, and Gemini use the bare host (gemini-3.1-pro-preview for
Gemini); Codex, OpenCode, OpenClaw, and Hermes use /v1 with gpt-5.5.

Marks isPartner with ?source=ccswitch attribution on apiKeyUrl only
(website URL stays clean). Adds the partnerPromotion blurb in all four
locales and a sponsor row in all four READMEs. Positioned after
ClaudeAPI in the Claude Code and Claude Desktop lists (the two apps
that carry a ClaudeAPI preset). Registers the favicon-derived code0.png
icon via URL import; the README banner is normalized to the standard
1920x798 aspect ratio.

src/config/codexProviderPresets.ts

@@ -364,6 +364,18 @@ export const codexProviderPresets: CodexProviderPreset[] = [
     endpointCandidates: ["https://api.amux.ai/v1"],
     icon: "amux",
   },
+  {
+    name: "Code0",
+    websiteUrl: "https://code0.ai",
+    apiKeyUrl: "https://code0.ai?source=ccswitch",
+    category: "aggregator",
+    auth: generateThirdPartyAuth(""),
+    config: generateThirdPartyConfig("code0", "https://code0.ai/v1", "gpt-5.5"),
+    endpointCandidates: ["https://code0.ai/v1"],
+    isPartner: true,
+    partnerPromotionKey: "code0",
+    icon: "code0",
+  },
   {
     name: "Azure OpenAI",
     websiteUrl: