feat(server/db): 数据层多库支持(1/4)— 连接分派 + 双方言迁移管线

- config 增 DB_DRIVER(mysql 默认 | sqlite);DSN 对 sqlite 为文件路径
- db.OpenDriver 按驱动分派:sqlite 用 modernc(纯 Go 免 CGO)+ WAL/
  busy_timeout/foreign_keys/_txlock=immediate;mysql 路径不变
- store.Open 分派;mysql 保留 UTC/collation 断言,sqlite 跳过
- 迁移拆 migrations/{mysql,sqlite}/ 双套,embed 双 FS,migrate 按驱动选源
  与 golang-migrate 驱动;修复 m.Close() 误关调用方 *sql.DB 的坑
- cmd/migrate 串入 DB_DRIVER;集成测试 MigrateUp 签名更新
- 新增 SQLite 时间往返 smoke 测试与端到端迁移测试(免 docker)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/internal/store/migrate.go

@@ -4,26 +4,29 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
+	"io/fs"
 
 	"github.com/golang-migrate/migrate/v4"
+	migratedb "github.com/golang-migrate/migrate/v4/database"
 	migratemysql "github.com/golang-migrate/migrate/v4/database/mysql"
+	migratesqlite "github.com/golang-migrate/migrate/v4/database/sqlite"
 	"github.com/golang-migrate/migrate/v4/source/iofs"
 
+	"github.com/wangjia/pangolin/server/internal/db"
 	"github.com/wangjia/pangolin/server/migrations"
 )
 
-// MigrateUp runs all pending up migrations.
-// migrate.ErrNoChange is treated as success (idempotent).
-func MigrateUp(db *sql.DB) error {
-	return runMigration(db, func(m *migrate.Migrate) error {
+// MigrateUp runs all pending up migrations for the given driver
+// ("mysql" | "sqlite"). migrate.ErrNoChange is treated as success (idempotent).
+func MigrateUp(database *sql.DB, driver string) error {
+	return runMigration(database, driver, func(m *migrate.Migrate) error {
 		return m.Up()
 	})
 }
 
-// MigrateDown rolls back all applied migrations.
-// migrate.ErrNoChange is treated as success.
-func MigrateDown(db *sql.DB) error {
-	return runMigration(db, func(m *migrate.Migrate) error {
+// MigrateDown rolls back all applied migrations. ErrNoChange = success.
+func MigrateDown(database *sql.DB, driver string) error {
+	return runMigration(database, driver, func(m *migrate.Migrate) error {
 		return m.Down()
 	})
 }
@@ -31,8 +34,8 @@ func MigrateDown(db *sql.DB) error {
 // MigrateVersion returns the currently applied migration version and whether
 // the schema is in a dirty state. Returns version 0 and no error when no
 // migrations have been applied yet.
-func MigrateVersion(db *sql.DB) (uint, bool, error) {
-	m, cleanup, err := newMigrator(db)
+func MigrateVersion(database *sql.DB, driver string) (uint, bool, error) {
+	m, cleanup, err := newMigrator(database, driver)
 	if err != nil {
 		return 0, false, err
 	}
@@ -49,8 +52,8 @@ func MigrateVersion(db *sql.DB) (uint, bool, error) {
 }
 
 // runMigration opens a migrator, calls fn, and handles ErrNoChange.
-func runMigration(db *sql.DB, fn func(*migrate.Migrate) error) error {
-	m, cleanup, err := newMigrator(db)
+func runMigration(database *sql.DB, driver string, fn func(*migrate.Migrate) error) error {
+	m, cleanup, err := newMigrator(database, driver)
 	if err != nil {
 		return err
 	}
@@ -63,30 +66,52 @@ func runMigration(db *sql.DB, fn func(*migrate.Migrate) error) error {
 }
 
 // newMigrator creates a golang-migrate instance backed by the embedded SQL
-// files (iofs source) and the provided *sql.DB (mysql driver instance).
-// The caller must invoke cleanup() to release source and driver resources.
-func newMigrator(db *sql.DB) (*migrate.Migrate, func(), error) {
-	src, err := iofs.New(migrations.FS, ".")
+// files for the chosen dialect and the provided *sql.DB. The caller must invoke
+// cleanup() to release source and driver resources.
+func newMigrator(database *sql.DB, driver string) (*migrate.Migrate, func(), error) {
+	embedFS, sub, dbName := migrationSource(driver)
+
+	src, err := iofs.New(embedFS, sub)
 	if err != nil {
 		return nil, nil, fmt.Errorf("store.migrate: iofs source: %w", err)
 	}
 
-	driver, err := migratemysql.WithInstance(db, &migratemysql.Config{})
+	mdriver, err := newMigrateDriver(driver, database)
 	if err != nil {
 		_ = src.Close()
-		return nil, nil, fmt.Errorf("store.migrate: mysql driver: %w", err)
+		return nil, nil, fmt.Errorf("store.migrate: %s driver: %w", dbName, err)
 	}
 
-	m, err := migrate.NewWithInstance("iofs", src, "mysql", driver)
+	m, err := migrate.NewWithInstance("iofs", src, dbName, mdriver)
 	if err != nil {
 		_ = src.Close()
-		_ = driver.Close()
+		_ = mdriver.Close()
 		return nil, nil, fmt.Errorf("store.migrate: new migrator: %w", err)
 	}
 
+	// Close only the embedded source, NOT the database driver: m.Close() would
+	// close the caller-owned *sql.DB (the WithInstance driver closes the handle
+	// it was given — fatal for a shared/in-memory connection the caller reuses).
+	// The caller owns the *sql.DB and closes it when done.
 	cleanup := func() {
-		// Close source and driver; errors here are non-fatal cleanup.
-		_, _ = m.Close()
+		_ = src.Close()
 	}
 	return m, cleanup, nil
 }
+
+// migrationSource returns the embedded FS, its subdir, and the golang-migrate
+// database name for the given driver.
+func migrationSource(driver string) (fs.FS, string, string) {
+	if db.Normalize(driver) == "sqlite" {
+		return migrations.SQLiteFS, "sqlite", "sqlite"
+	}
+	return migrations.MySQLFS, "mysql", "mysql"
+}
+
+// newMigrateDriver builds the golang-migrate database driver for the dialect.
+func newMigrateDriver(driver string, database *sql.DB) (migratedb.Driver, error) {
+	if db.Normalize(driver) == "sqlite" {
+		return migratesqlite.WithInstance(database, &migratesqlite.Config{})
+	}
+	return migratemysql.WithInstance(database, &migratemysql.Config{})
+}