feat(providers): add DMXAPI as official partner

Mark DMXAPI as partner in both Claude and Codex presets with promotion
message for their Claude Code exclusive model 66% OFF offer.

src/config/claudeProviderPresets.ts

@@ -350,6 +350,8 @@ export const providerPresets: ProviderPreset[] = [
     // 请求地址候选（用于地址管理/测速），用户可自行选择/覆盖
     endpointCandidates: ["https://www.dmxapi.cn", "https://api.dmxapi.cn"],
     category: "aggregator",
+    isPartner: true, // 合作伙伴
+    partnerPromotionKey: "dmxapi", // 促销信息 i18n key
   },
   {
     name: "PackyCode",

src/config/codexProviderPresets.ts

@@ -131,6 +131,8 @@ requires_openai_auth = true`,
       "gpt-5.1-codex",
     ),
     endpointCandidates: ["https://www.dmxapi.cn/v1"],
+    isPartner: true, // 合作伙伴
+    partnerPromotionKey: "dmxapi", // 促销信息 i18n key
   },
   {
     name: "PackyCode",