revert: completely remove all Sora functionality

backend/internal/pkg/openai/oauth.go

@@ -17,8 +17,6 @@ import (
 const (
 	// OAuth Client ID for OpenAI (Codex CLI official)
 	ClientID = "app_EMoamEEZ73f0CkXaXp7hrann"
-	// OAuth Client ID for Sora mobile flow (aligned with sora2api)
-	SoraClientID = "app_LlGpXReQgckcGGUo2JrYvtJK"
 
 	// OAuth endpoints
 	AuthorizeURL = "https://auth.openai.com/oauth/authorize"
@@ -39,8 +37,6 @@ const (
 const (
 	// OAuthPlatformOpenAI uses OpenAI Codex-compatible OAuth client.
 	OAuthPlatformOpenAI = "openai"
-	// OAuthPlatformSora uses Sora OAuth client.
-	OAuthPlatformSora = "sora"
 )
 
 // OAuthSession stores OAuth flow state for OpenAI
@@ -211,15 +207,8 @@ func BuildAuthorizationURLForPlatform(state, codeChallenge, redirectURI, platfor
 }
 
 // OAuthClientConfigByPlatform returns oauth client_id and whether codex simplified flow should be enabled.
-// Sora 授权流程复用 Codex CLI 的 client_id（支持 localhost redirect_uri），
-// 但不启用 codex_cli_simplified_flow；拿到的 access_token 绑定同一 OpenAI 账号，对 Sora API 同样可用。
 func OAuthClientConfigByPlatform(platform string) (clientID string, codexFlow bool) {
-	switch strings.ToLower(strings.TrimSpace(platform)) {
-	case OAuthPlatformSora:
-		return ClientID, false
-	default:
-		return ClientID, true
-	}
+	return ClientID, true
 }
 
 // TokenRequest represents the token exchange request body