Refactor: Implement uber-go/fx dependency injection

- Replace global variable pattern with proper dependency injection
- Add uber-go/fx for automatic dependency resolution
- Refactor all services and handlers to use constructor injection
- Eliminate fragile initialization order dependencies
- Improve testability and modularity
- Add structured logging with zap

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

internal/services/imgKitHelper.go

@@ -3,24 +3,23 @@ package services
 import "CatsOfMastodonBotGo/internal/config"
 
 type ImgKitHelper struct {
+	cfg *config.Config
 }
 
-var ImgKitHelperInstance *ImgKitHelper
-
-func InitImgKitHelper() {
-	ImgKitHelperInstance = &ImgKitHelper{}
+func NewImgKitHelper(cfg *config.Config) *ImgKitHelper {
+	return &ImgKitHelper{cfg: cfg}
 }
 
-func GetPreviewUrl(url string) string {
-	if config.Config.ImageKitId == "" {
+func (ikh *ImgKitHelper) GetPreviewUrl(url string) string {
+	if ikh.cfg.ImageKitId == "" {
 		return url
 	}
-	return "https://ik.imagekit.io/" + config.Config.ImageKitId + "/tr:w-500,h-500,c-at_max,f-webp,q-50/" + url
+	return "https://ik.imagekit.io/" + ikh.cfg.ImageKitId + "/tr:w-500,h-500,c-at_max,f-webp,q-50/" + url
 }
 
-func GetRemoteUrl(url string) string {
-	if config.Config.ImageKitId == "" {
+func (ikh *ImgKitHelper) GetRemoteUrl(url string) string {
+	if ikh.cfg.ImageKitId == "" {
 		return url
 	}
-	return "https://ik.imagekit.io/" + config.Config.ImageKitId + "/tr:q-70,dpr-auto,f-webp/" + url
-}
+	return "https://ik.imagekit.io/" + ikh.cfg.ImageKitId + "/tr:q-70,dpr-auto,f-webp/" + url
+}