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_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))
+	}
+}