merge: config + store(UTC DSN) + 自动迁移 [tsk_zRA6fGU1JuHj]

以 main 现有 config 设计为准(FromEnv/*Config/单 DSN/RS256),移植分支新增的 store 层:mysql.go 的 Open(*config.Config) 改用 cfg.DSN、结构化强制 UTC + 会话时区断言;migrate.go + migrations/embed.go 提供 golang-migrate 嵌入式迁移;cmd/migrate/main.go 实现 migrate CLI(读 DB_DSN)。未采用分支的 Load()/PANGOLIN_ 前缀/MySQL 拆分字段(与 main 设计冲突)。

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

server/cmd/migrate/main.go

@@ -1,14 +1,73 @@
+// Command migrate applies or reverts database schema migrations for the
+// Pangolin server.
+//
+// Usage:
+//
+//	migrate up       – apply all pending migrations
+//	migrate down     – revert all applied migrations
+//	migrate version  – print the current migration version
+//
+// Configuration is read from the DB_DSN environment variable (a full MySQL
+// DSN), consistent with the rest of the server.
 package main
 
 import (
 	"fmt"
+	"log"
 	"os"
+
+	"github.com/wangjia/pangolin/server/internal/config"
+	"github.com/wangjia/pangolin/server/internal/store"
 )
 
 func main() {
-	fmt.Fprintln(os.Stdout, "pangolin-migrate: database migration tool")
-	fmt.Fprintln(os.Stdout, "Usage: migrate [-up|-down] [-steps N]")
-	fmt.Fprintln(os.Stdout, "")
-	fmt.Fprintln(os.Stdout, "  (implementation in task 1e)")
-	os.Exit(0)
+	if len(os.Args) < 2 {
+		usage()
+		os.Exit(1)
+	}
+	cmd := os.Args[1]
+
+	dsn := os.Getenv("DB_DSN")
+	if dsn == "" {
+		log.Fatal("migrate: DB_DSN is required")
+	}
+
+	db, err := store.Open(&config.Config{DSN: dsn})
+	if err != nil {
+		log.Fatalf("migrate: db: %v", err)
+	}
+	defer db.Close()
+
+	switch cmd {
+	case "up":
+		if err := store.MigrateUp(db); err != nil {
+			log.Fatalf("migrate up: %v", err)
+		}
+		log.Println("migrate: up — done")
+
+	case "down":
+		if err := store.MigrateDown(db); err != nil {
+			log.Fatalf("migrate down: %v", err)
+		}
+		log.Println("migrate: down — done")
+
+	case "version":
+		version, dirty, err := store.MigrateVersion(db)
+		if err != nil {
+			log.Fatalf("migrate version: %v", err)
+		}
+		fmt.Printf("migrate: version=%d dirty=%v\n", version, dirty)
+
+	default:
+		fmt.Fprintf(os.Stderr, "migrate: unknown command %q\n", cmd)
+		usage()
+		os.Exit(1)
+	}
+}
+
+func usage() {
+	fmt.Fprintln(os.Stderr, "Usage: migrate <up|down|version>")
+	fmt.Fprintln(os.Stderr, "")
+	fmt.Fprintln(os.Stderr, "Environment variables:")
+	fmt.Fprintln(os.Stderr, "  DB_DSN   full MySQL DSN (required)")
 }