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/web/handlers/embedCard.go

@@ -7,21 +7,24 @@ import (
 )
 
 type EmbedCardHandler struct {
-	PostService services.PostService
+	postService  *services.PostService
+	imgKitHelper *services.ImgKitHelper
 }
 
-var EmbedCardHandlerInstance *EmbedCardHandler
-
-func InitEmbedCardHandler() {
-	EmbedCardHandlerInstance = &EmbedCardHandler{
-		PostService: *services.PostServiceInstance,
+func NewEmbedCardHandler(
+	postService *services.PostService,
+	imgKitHelper *services.ImgKitHelper,
+) *EmbedCardHandler {
+	return &EmbedCardHandler{
+		postService:  postService,
+		imgKitHelper: imgKitHelper,
 	}
 }
 
-func (ps *EmbedCardHandler) GetEmbedCard(c *gin.Context) {
-	post := ps.PostService.GetRandomPost()
+func (ech *EmbedCardHandler) GetEmbedCard(c *gin.Context) {
+	post := ech.postService.GetRandomPost()
 	c.HTML(200, "home/embed.html", gin.H{
 		"postUrl":  post.Url,
-		"imageUrl": services.GetRemoteUrl(post.Attachments[0].RemoteUrl),
+		"imageUrl": ech.imgKitHelper.GetRemoteUrl(post.Attachments[0].RemoteUrl),
 	})
-}
+}