fix: Update Kimi preset to coding endpoint

Kimi Code documents a separate Anthropic-compatible coding endpoint from the Moonshot open platform, so the built-in Kimi preset should point Claude-compatible traffic at the coding endpoint instead of the retired Moonshot anthropic path.

Constraint: Kimi Code Anthropic-compatible base URL is https://api.kimi.com/coding/ and this app appends /v1/messages at runtime.
Rejected: Use https://api.moonshot.cn/coding | official Kimi docs distinguish Kimi Code from the Moonshot open platform URLs.
Confidence: high
Scope-risk: narrow
Directive: Do not switch Kimi back to api.moonshot.cn/anthropic without rechecking current Kimi Code docs.
Tested: bun test src/server/__tests__/provider-presets.test.ts
Not-tested: Live Kimi API call with a real user key

src/server/__tests__/provider-presets.test.ts

@@ -66,6 +66,7 @@ describe('provider presets API', () => {
     expect(zhipu?.defaultModels.haiku).toBe('glm-4.5-air')
     expect(zhipu?.defaultModels.sonnet).toBe('glm-5-turbo')
     expect(zhipu?.defaultModels.opus).toBe('glm-5.1')
+    expect(kimi?.baseUrl).toBe('https://api.kimi.com/coding')
     expect(kimi?.defaultModels.main).toBe('kimi-k2.6')
     expect(minimax?.defaultModels.main).toBe('MiniMax-M2.7')
   })

src/server/config/providerPresets.json

@@ -44,7 +44,7 @@
   {
     "id": "kimi",
     "name": "Kimi",
-    "baseUrl": "https://api.moonshot.cn/anthropic",
+    "baseUrl": "https://api.kimi.com/coding",
     "apiFormat": "anthropic",
     "defaultModels": {
       "main": "kimi-k2.6",