feat(moderation): add Tencent TMS as fallback for AI content moderation

Add Tencent Cloud Text Moderation System (TMS) as a fallback moderation
service when OpenAI is unavailable or returns an error. The service
now checks OpenAI first, and falls back to Tencent TMS if it fails,
providing better reliability for content moderation.

Features:
- New Tencent TMS configuration in config.yaml with environment variable overrides
- New tencent package in internal/pkg/tencent/ with TMS client implementation
- PostAIService now uses dual moderation with OpenAI primary and Tencent fallback
- Strict mode configuration passed to PostAIService for consistent behavior

BREAKING CHANGE: NewPostAIService now requires tencentClient and strictMode
parameters - update wire configuration accordingly.

internal/wire/infrastructure.go

@@ -12,6 +12,7 @@ import (
 	"carrot_bbs/internal/pkg/openai"
 	"carrot_bbs/internal/pkg/redis"
 	"carrot_bbs/internal/pkg/s3"
+	"carrot_bbs/internal/pkg/tencent"
 	"carrot_bbs/internal/pkg/ws"
 	"carrot_bbs/internal/repository"
 	"carrot_bbs/internal/service"
@@ -49,6 +50,7 @@ var InfrastructureSet = wire.NewSet(
 
 	// 外部服务客户端
 	ProvideOpenAIClient,
+	ProvideTencentClient,
 	ProvideEmailClient,
 	ProvideS3Client,
 
@@ -169,6 +171,18 @@ func ProvideOpenAIClient(cfg *config.Config) openai.Client {
 	return openai.NewClient(openai.ConfigFromAppConfig(&cfg.OpenAI))
 }
 
+// ProvideTencentClient 提供腾讯云TMS客户端
+func ProvideTencentClient(cfg *config.Config) tencent.Client {
+	return tencent.NewClient(tencent.Config{
+		Enabled:   cfg.TencentTMS.Enabled,
+		SecretID:  cfg.TencentTMS.SecretID,
+		SecretKey: cfg.TencentTMS.SecretKey,
+		Region:    cfg.TencentTMS.Region,
+		BizType:   cfg.TencentTMS.BizType,
+		Timeout:   cfg.TencentTMS.Timeout,
+	})
+}
+
 // ProvideEmailClient 提供邮件客户端
 func ProvideEmailClient(cfg *config.Config) email.Client {
 	return email.NewClient(email.ConfigFromAppConfig(&cfg.Email))

internal/wire/service.go

@@ -11,6 +11,7 @@ import (
 	"carrot_bbs/internal/pkg/openai"
 	"carrot_bbs/internal/pkg/redis"
 	"carrot_bbs/internal/pkg/s3"
+	"carrot_bbs/internal/pkg/tencent"
 	"carrot_bbs/internal/pkg/ws"
 	"carrot_bbs/internal/repository"
 	"carrot_bbs/internal/service"
@@ -87,8 +88,8 @@ func ProvideEmailService(client email.Client) service.EmailService {
 }
 
 // ProvidePostAIService 提供 AI 服务
-func ProvidePostAIService(client openai.Client) *service.PostAIService {
-	return service.NewPostAIService(client)
+func ProvidePostAIService(openAIClient openai.Client, tencentClient tencent.Client, cfg *config.Config) *service.PostAIService {
+	return service.NewPostAIService(openAIClient, tencentClient, cfg.OpenAI.StrictModeration)
 }
 
 // ProvidePushService 提供推送服务