chore: optimize SEO and fix golangci-lint issues

- Implement dynamic SEO meta tags and sitemap.xml for toolbox.pengzhan.dev
- Fix SPA title/meta refresh issue in layout.html
- Address golangci-lint findings:
  - Refactor switch-case for tool path and SVG token parsing
  - Replace math.Pow with direct multiplication for performance
  - Fix unhandled error returns and unused imports
  - Omit redundant type declarations

pkg/zitie/tool.go

@@ -28,10 +28,12 @@ func init() {
 	base.Register(&zitieTool{})
 }
 
-func (t *zitieTool) ID() string          { return "zitie" }
-func (t *zitieTool) Name() string        { return "汉字字帖生成" }
-func (t *zitieTool) Description() string { return "提供智能缺字处理和古风排版的专业字帖工具" }
-func (t *zitieTool) Emoji() string       { return "🎨" }
+func (t *zitieTool) ID() string   { return "zitie" }
+func (t *zitieTool) Name() string { return "汉字字帖生成" }
+func (t *zitieTool) Description() string {
+	return "提供智能缺字处理和古风排版的专业字帖工具"
+}
+func (t *zitieTool) Emoji() string { return "🎨" }
 
 func (t *zitieTool) Init() error {
 	fmt.Println("Initializing Zitie tool with font check...")
@@ -39,21 +41,23 @@ func (t *zitieTool) Init() error {
 	if err := json.Unmarshal(allDataContent, &t.allChars); err != nil {
 		return fmt.Errorf("failed to unmarshal all.json: %v", err)
 	}
-	
+
 	fontBytes, _ := fontFS.ReadFile("data/font.ttf")
 	logic.SetFontData(fontBytes)
 
 	fonts := map[string]string{
-		"kaiti":    "data/kaiti.ttf",
-		"lishu":    "data/lishu.ttf",
-		"xingshu":  "data/xingshu.ttf",
-		"songti":   "data/songti.ttf",
+		"kaiti":   "data/kaiti.ttf",
+		"lishu":   "data/lishu.ttf",
+		"xingshu": "data/xingshu.ttf",
+		"songti":  "data/songti.ttf",
 	}
 
 	for id, src := range fonts {
 		bytes, err := fontFS.ReadFile(src)
-		if err != nil { continue }
-		
+		if err != nil {
+			continue
+		}
+
 		// 1. 同步到磁盘用于 gopdf
 		tmpPath := filepath.Join(os.TempDir(), fmt.Sprintf("own_tools_%s.ttf", id))
 		_ = os.WriteFile(tmpPath, bytes, 0644)
@@ -66,7 +70,7 @@ func (t *zitieTool) Init() error {
 			fmt.Printf("Font [%s] analyzed and registered\n", id)
 		}
 	}
-	
+
 	return nil
 }
 
@@ -79,7 +83,7 @@ func (t *zitieTool) RegisterRoutes(r *gin.RouterGroup) {
 type ZitieRequest struct {
 	Chars     string `json:"chars" binding:"required"`
 	PaperSize string `json:"paper_size"`
-	FontType  string `json:"font_type"` 
+	FontType  string `json:"font_type"`
 }
 
 func (t *zitieTool) handleTeaching(c *gin.Context) {
@@ -108,7 +112,9 @@ func (t *zitieTool) handleManuscript(c *gin.Context) {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
 		return
 	}
-	if req.FontType == "" { req.FontType = "kaiti" }
+	if req.FontType == "" {
+		req.FontType = "kaiti"
+	}
 	data := t.filterChars(req.Chars, true)
 	t.generateAndResponse(c, data, "manuscript", req.PaperSize, req.FontType)
 }
@@ -117,18 +123,29 @@ func (t *zitieTool) filterChars(input string, keepNewline bool) []logic.HanziDat
 	var res []logic.HanziData
 	// 扩充标点符号列表
 	puncs := "，。！？；：、“”（）《》〈〉…·.?!,:;\"'()<> 「」【】『』〔〕"
-	
+
 	for _, r := range input {
 		charStr := string(r)
 		if r == '\n' {
-			if keepNewline { res = append(res, logic.HanziData{Character: "\n"}) }
+			if keepNewline {
+				res = append(res, logic.HanziData{Character: "\n"})
+			}
 			continue
 		}
-		if r == ' ' || r == '\r' || r == '\t' { continue }
-		
+		if r == ' ' || r == '\r' || r == '\t' {
+			continue
+		}
+
 		isPunc := false
-		for _, p := range puncs { if r == p { isPunc = true; break } }
-		if isPunc { continue }
+		for _, p := range puncs {
+			if r == p {
+				isPunc = true
+				break
+			}
+		}
+		if isPunc {
+			continue
+		}
 
 		if hd, ok := t.allChars[charStr]; ok {
 			hd.Character = charStr