test: H-02 补充 migrations 测试

- 验证迁移文件正确嵌入 embed.FS
- 测试所有迁移文件可读且非空
- 验证迁移文件命名规范（NNNN_前缀）
- 测试迁移文件排序一致性
- 验证初始迁移文件包含预期 SQL 内容

internal/store/migrations/embed_test.go

@@ -0,0 +1,171 @@
+package migrations
+
+import (
+	"testing"
+)
+
+func TestFilesEmbedded(t *testing.T) {
+	// Test that migration files are properly embedded
+	entries, err := Files.ReadDir(".")
+	if err != nil {
+		t.Fatalf("Failed to read embedded migrations: %v", err)
+	}
+
+	if len(entries) == 0 {
+		t.Fatal("No migration files embedded")
+	}
+
+	// Verify we have SQL files
+	hasSQL := false
+	for _, entry := range entries {
+		if !entry.IsDir() && len(entry.Name()) > 4 && entry.Name()[len(entry.Name())-4:] == ".sql" {
+			hasSQL = true
+			break
+		}
+	}
+
+	if !hasSQL {
+		t.Fatal("No .sql files found in embedded migrations")
+	}
+}
+
+func TestMigrationFilesReadable(t *testing.T) {
+	// Test that all embedded migration files can be read
+	entries, err := Files.ReadDir(".")
+	if err != nil {
+		t.Fatalf("Failed to read embedded migrations: %v", err)
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+
+		// Skip non-SQL files
+		name := entry.Name()
+		if len(name) < 4 || name[len(name)-4:] != ".sql" {
+			continue
+		}
+
+		content, err := Files.ReadFile(name)
+		if err != nil {
+			t.Errorf("Failed to read migration file %s: %v", name, err)
+			continue
+		}
+
+		if len(content) == 0 {
+			t.Errorf("Migration file %s is empty", name)
+		}
+
+		// Verify content looks like SQL
+		contentStr := string(content)
+		if len(contentStr) < 10 {
+			t.Errorf("Migration file %s content too short", name)
+		}
+	}
+}
+
+func TestMigrationFileNaming(t *testing.T) {
+	// Test that migration files follow naming convention (NNNN_description.sql)
+	entries, err := Files.ReadDir(".")
+	if err != nil {
+		t.Fatalf("Failed to read embedded migrations: %v", err)
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+
+		name := entry.Name()
+		if len(name) < 4 || name[len(name)-4:] != ".sql" {
+			continue
+		}
+
+		// Check naming pattern: should start with digits followed by underscore
+		if len(name) < 5 {
+			t.Errorf("Migration file %s name too short", name)
+			continue
+		}
+
+		// Should start with at least 4 digits
+		hasPrefix := false
+		for i := 0; i < 4 && i < len(name); i++ {
+			if name[i] >= '0' && name[i] <= '9' {
+				if i == 3 {
+					hasPrefix = true
+				}
+			} else {
+				break
+			}
+		}
+
+		if !hasPrefix {
+			t.Errorf("Migration file %s does not follow naming convention (should start with 4 digits)", name)
+		}
+	}
+}
+
+func TestMigrationFilesSorted(t *testing.T) {
+	// Test that migration files can be sorted consistently
+	entries, err := Files.ReadDir(".")
+	if err != nil {
+		t.Fatalf("Failed to read embedded migrations: %v", err)
+	}
+
+	var sqlFiles []string
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		name := entry.Name()
+		if len(name) > 4 && name[len(name)-4:] == ".sql" {
+			sqlFiles = append(sqlFiles, name)
+		}
+	}
+
+	if len(sqlFiles) < 2 {
+		t.Skip("Not enough SQL files to test sorting")
+	}
+
+	// Verify files can be compared
+	for i := 1; i < len(sqlFiles); i++ {
+		if sqlFiles[i] < sqlFiles[i-1] {
+			t.Errorf("Files not sorted: %s should come before %s", sqlFiles[i-1], sqlFiles[i])
+		}
+	}
+}
+
+func TestInitialMigrationContent(t *testing.T) {
+	// Test that the initial migration file exists and has expected content
+	content, err := Files.ReadFile("0001_init.sql")
+	if err != nil {
+		t.Skipf("0001_init.sql not found: %v", err)
+	}
+
+	contentStr := string(content)
+
+	// Initial migration should contain CREATE TABLE statements
+	if len(contentStr) < 50 {
+		t.Error("Initial migration file seems too short")
+	}
+
+	// Should contain typical SQL keywords
+	hasCreate := containsAny(contentStr, []string{"CREATE", "create"})
+	hasTable := containsAny(contentStr, []string{"TABLE", "table"})
+
+	if !hasCreate || !hasTable {
+		t.Error("Initial migration should contain CREATE TABLE statements")
+	}
+}
+
+func containsAny(s string, substrs []string) bool {
+	for _, substr := range substrs {
+		for i := 0; i <= len(s)-len(substr); i++ {
+			if s[i:i+len(substr)] == substr {
+				return true
+			}
+		}
+	}
+	return false
+}