fix(oauth): enhance error handling and transaction management for OAuth user creation and binding

- Improve error handling in DeleteCustomOAuthProvider to log and return errors when fetching binding counts.
- Refactor user creation and OAuth binding logic to use transactions for atomic operations, ensuring data integrity.
- Add unique constraints to UserOAuthBinding model to prevent duplicate bindings.
- Enhance GitHub OAuth provider error logging for non-200 responses.
- Update AccountManagement component to provide clearer error messages on API failures.

oauth/github.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 	"strconv"
 	"time"
@@ -122,6 +123,17 @@ func (p *GitHubProvider) GetUserInfo(ctx context.Context, token *OAuthToken) (*O
 
 	logger.LogDebug(ctx, "[OAuth-GitHub] GetUserInfo response status: %d", res.StatusCode)
 
+	// Check for non-200 status codes before attempting to decode
+	if res.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(res.Body)
+		bodyStr := string(body)
+		if len(bodyStr) > 500 {
+			bodyStr = bodyStr[:500] + "..."
+		}
+		logger.LogError(ctx, fmt.Sprintf("[OAuth-GitHub] GetUserInfo failed: status=%d, body=%s", res.StatusCode, bodyStr))
+		return nil, NewOAuthErrorWithRaw(i18n.MsgOAuthGetUserErr, map[string]any{"Provider": "GitHub"}, fmt.Sprintf("status %d", res.StatusCode))
+	}
+
 	var githubUser gitHubUser
 	err = json.NewDecoder(res.Body).Decode(&githubUser)
 	if err != nil {