feat: implement dynamic changelog loading from API

- Add GET /api/changelog endpoint to fetch changelog from CHANGELOG.md
- Create service/changelog.go to parse CHANGELOG.md markdown file
- Add handler/changelog.go to handle changelog requests
- Update ChangelogDrawer component to fetch from API instead of hardcoded data
- Export apiFetch from lib/api.ts for public use
- Add changelog parser tests with 14 version entries verified

server/service/changelog.go

@@ -0,0 +1,125 @@
+package service
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// ChangelogEntry 变更日志条目
+type ChangelogEntry struct {
+	Version string              `json:"version"`
+	Date    string              `json:"date"`
+	Changes map[string][]string `json:"changes"`
+}
+
+// ParseChangelog 解析 CHANGELOG.md 文件
+func ParseChangelog() ([]ChangelogEntry, error) {
+	// 获取项目根目录
+	rootDir := os.Getenv("PROJECT_ROOT")
+	if rootDir == "" {
+		// 如果未设置，使用相对路径推测
+		rootDir = ".."
+	}
+
+	changelogPath := filepath.Join(rootDir, "CHANGELOG.md")
+
+	file, err := os.Open(changelogPath)
+	if err != nil {
+		return nil, fmt.Errorf("打开 CHANGELOG.md 失败: %w", err)
+	}
+	defer file.Close()
+
+	var entries []ChangelogEntry
+	var currentEntry *ChangelogEntry
+	var currentCategory string
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		// 匹配版本号行 ## [1.4.0] - 2026-03-23
+		if strings.HasPrefix(line, "## [") && strings.Contains(line, "]") {
+			// 保存前一个 entry
+			if currentEntry != nil {
+				entries = append(entries, *currentEntry)
+			}
+
+			// 解析版本号和日期
+			version, date := parseVersionLine(line)
+			if version != "" && version != "Unreleased" {
+				currentEntry = &ChangelogEntry{
+					Version: version,
+					Date:    date,
+					Changes: make(map[string][]string),
+				}
+				currentCategory = ""
+			} else {
+				currentEntry = nil
+			}
+			continue
+		}
+
+		// 跳过 Unreleased 和其他非版本行
+		if currentEntry == nil {
+			continue
+		}
+
+		// 匹配分类行 ### 新增、### 优化等
+		if strings.HasPrefix(line, "### ") {
+			currentCategory = strings.TrimPrefix(line, "### ")
+			if currentEntry.Changes[currentCategory] == nil {
+				currentEntry.Changes[currentCategory] = []string{}
+			}
+			continue
+		}
+
+		// 匹配项目行 - 项目描述
+		if strings.HasPrefix(line, "- ") && currentCategory != "" {
+			item := strings.TrimPrefix(line, "- ")
+			// 移除加粗标记和链接等
+			item = cleanItem(item)
+			currentEntry.Changes[currentCategory] = append(currentEntry.Changes[currentCategory], item)
+		}
+	}
+
+	// 保存最后一个 entry
+	if currentEntry != nil {
+		entries = append(entries, *currentEntry)
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, fmt.Errorf("扫描文件失败: %w", err)
+	}
+
+	return entries, nil
+}
+
+// parseVersionLine 解析版本行 ## [1.4.0] - 2026-03-23
+func parseVersionLine(line string) (version, date string) {
+	// 提取版本号
+	startIdx := strings.Index(line, "[")
+	endIdx := strings.Index(line, "]")
+	if startIdx >= 0 && endIdx > startIdx {
+		version = line[startIdx+1 : endIdx]
+	}
+
+	// 提取日期
+	dateStartIdx := strings.LastIndex(line, "- ") + 2
+	if dateStartIdx > 1 {
+		date = strings.TrimSpace(line[dateStartIdx:])
+	}
+
+	return
+}
+
+// cleanItem 清理项目描述（移除加粗标记等）
+func cleanItem(item string) string {
+	// 移除加粗标记 **text**
+	item = strings.ReplaceAll(item, "**", "")
+	// 移除代码标记 `text`
+	item = strings.ReplaceAll(item, "`", "")
+	return strings.TrimSpace(item)
+}

server/service/changelog_test.go

@@ -0,0 +1,38 @@
+package service
+
+import (
+	"os"
+	"testing"
+)
+
+func TestParseChangelog(t *testing.T) {
+	// 设置项目根目录
+	os.Setenv("PROJECT_ROOT", "../..")
+
+	changelog, err := ParseChangelog()
+	if err != nil {
+		t.Fatalf("ParseChangelog failed: %v", err)
+	}
+
+	if len(changelog) == 0 {
+		t.Fatal("No changelog entries parsed")
+	}
+
+	// 验证第一个条目（应该是 1.4.0）
+	firstEntry := changelog[0]
+	t.Logf("First entry: v%s - %s", firstEntry.Version, firstEntry.Date)
+
+	if firstEntry.Version != "1.4.0" {
+		t.Errorf("Expected first version to be 1.4.0, got %s", firstEntry.Version)
+	}
+
+	if len(firstEntry.Changes) == 0 {
+		t.Error("First entry has no changes")
+	}
+
+	// 打印所有版本
+	t.Logf("Total versions: %d", len(changelog))
+	for _, entry := range changelog {
+		t.Logf("  - v%s: %d categories", entry.Version, len(entry.Changes))
+	}
+}