feat(server): notify mcp-server billing_provider=newapi after Agnet user sync

Implements Heicode's choice (b) for §7.7.1 ②: in syncLocalUserFromAgnet,
fire-and-forget PUT mcp-server's internal /api/auth/internal/billing-provider
{email, billing_provider:"newapi"} so mcp-server's User table billing_provider
column lands as 'newapi' for users that came in via Heicode Manager (vs the
default 'litellm' for native taijiagent users).

- Goroutine: never blocks login on this side-effect; mcp-server endpoint is
  idempotent so retries from repeat logins are harmless.
- Token via env MCP_SERVER_INTERNAL_TOKEN (K8s/compose secret); empty env
  silently skips (dev-friendly).
- Reuses agnetHTTPClient + common.Marshal + common.GetUUID per repo
  conventions.

Spec: docs/Heicode-对接进度与待办.md §7.8.1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

heicode/controller/heicode_agnet_session.go

@@ -174,6 +174,61 @@ func fetchAgnetRefresh(baseURL, refreshToken string) (access string, refresh str
 	return env.Data.Token, env.Data.RefreshToken, nil
 }
 
+// markBillingProviderNewapi notifies mcp-server that this user's billing
+// provider should be set to "newapi" (per Heicode 决策 7.7.1 ②).
+//
+// Fire-and-forget: 失败不影响登录主流程；mcp-server 那边也允许重复调用
+// （内部端点对相同 email 幂等）。详见 Heicode-对接进度与待办.md §7.8.1。
+//
+// Token 通过 K8s secret / docker compose env `MCP_SERVER_INTERNAL_TOKEN`
+// 注入；未配置时跳过（开发环境兼容）。
+func markBillingProviderNewapi(email string) {
+	tok := strings.TrimSpace(os.Getenv("MCP_SERVER_INTERNAL_TOKEN"))
+	if tok == "" {
+		return
+	}
+	email = strings.TrimSpace(email)
+	if email == "" {
+		return
+	}
+	go func(email, tok string) {
+		body, err := common.Marshal(map[string]string{
+			"email":            email,
+			"billing_provider": "newapi",
+		})
+		if err != nil {
+			common.SysLog("markBillingProviderNewapi: marshal failed: " + err.Error())
+			return
+		}
+		baseURL := defaultHeicodeAuthBaseURL()
+		req, err := http.NewRequest(
+			http.MethodPut,
+			baseURL+"/api/auth/internal/billing-provider",
+			strings.NewReader(string(body)),
+		)
+		if err != nil {
+			common.SysLog("markBillingProviderNewapi: req build failed: " + err.Error())
+			return
+		}
+		req.Header.Set("Authorization", "Bearer "+tok)
+		req.Header.Set("Content-Type", "application/json")
+		req.Header.Set("X-Request-Id", common.GetUUID())
+		res, err := agnetHTTPClient().Do(req)
+		if err != nil {
+			common.SysLog("markBillingProviderNewapi: send failed: " + err.Error())
+			return
+		}
+		defer res.Body.Close()
+		if res.StatusCode >= 400 {
+			b, _ := io.ReadAll(io.LimitReader(res.Body, 1<<14))
+			common.SysLog(fmt.Sprintf(
+				"markBillingProviderNewapi: %d %s — %s",
+				res.StatusCode, email, strings.TrimSpace(string(b)),
+			))
+		}
+	}(email, tok)
+}
+
 func syncLocalUserFromAgnet(me agnetMeEnvelope) (*model.User, error) {
 	email := strings.TrimSpace(me.Data.Email)
 	if email == "" {
@@ -242,6 +297,9 @@ func syncLocalUserFromAgnet(me agnetMeEnvelope) (*model.User, error) {
 		}
 	}
 
+	// Notify mcp-server billing_provider=newapi (fire-and-forget; goroutine).
+	markBillingProviderNewapi(user.Email)
+
 	return &user, nil
 }