chore: point feishu brand to PPE for view_url integration test

Debug-only: switch the default Open endpoint to open.feishu-pre.cn and
inject x-tt-env: ppe_agent_view so requests land in the PPE lane. Not
for merge into main.

internal/cmdutil/secheader.go

@@ -55,6 +55,7 @@ func BaseSecurityHeaders() http.Header {
 	if v := envvars.AgentTrace(); v != "" {
 		h.Set(HeaderAgentTrace, v)
 	}
+	h.Set("x-tt-env", "ppe_agent_view")
 	return h
 }
 

internal/core/types.go

@@ -51,7 +51,7 @@ func ResolveEndpoints(brand LarkBrand) Endpoints {
 		}
 	default:
 		return Endpoints{
-			Open:     "https://open.feishu.cn",
+			Open:     "https://open.feishu-pre.cn",
 			Accounts: "https://accounts.feishu.cn",
 			MCP:      "https://mcp.feishu.cn",
 			AppLink:  "https://applink.feishu.cn",