feat(backend): bcrypt+jwt auth package and admin seeding

backend/internal/seed/seed_test.go

@@ -0,0 +1,41 @@
+package seed
+
+import (
+	"context"
+	"os"
+	"testing"
+
+	"booklib/internal/db"
+	"booklib/internal/store"
+)
+
+func TestSeedOnlyWhenEmpty(t *testing.T) {
+	url := os.Getenv("DATABASE_URL")
+	if url == "" {
+		t.Skip("DATABASE_URL not set")
+	}
+	ctx := context.Background()
+	p, _ := db.Connect(ctx, url)
+	if err := db.Migrate(ctx, p); err != nil {
+		t.Fatal(err)
+	}
+	s := store.New(p)
+	p.Exec(ctx, "DELETE FROM reading_progress; DELETE FROM books; DELETE FROM libraries; DELETE FROM users")
+	if err := Admin(ctx, s, "admin", "pw12345"); err != nil {
+		t.Fatal(err)
+	}
+	if err := Admin(ctx, s, "admin2", "pw12345"); err != nil { // 已有用户 → no-op
+		t.Fatal(err)
+	}
+	n, _ := s.CountUsers(ctx)
+	if n != 1 {
+		t.Fatalf("want 1 user got %d", n)
+	}
+	u, err := s.GetUserByName(ctx, "admin")
+	if err != nil || u.Role != "admin" {
+		t.Fatalf("bad admin: %+v %v", u, err)
+	}
+	if err := Admin(ctx, s, "", ""); err != nil {
+		t.Fatal("empty creds must no-op, got", err)
+	}
+}