使用了AI重构项目，并完善了一部分后台问题

internal/config/config_test.go

@@ -0,0 +1,26 @@
+package config
+
+import "testing"
+
+func TestSecretRoundTripAndIsolation(t *testing.T) {
+	first := &Config{EncryptionKey: []byte("01234567890123456789012345678901")}
+	second := &Config{EncryptionKey: []byte("abcdefghijklmnopqrstuvwxyz123456")}
+	ciphertext, err := first.EncryptSecret("umami-secret")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if ciphertext == "umami-secret" || ciphertext == "" {
+		t.Fatalf("secret was not encrypted: %q", ciphertext)
+	}
+	plaintext, err := first.DecryptSecret(ciphertext)
+	if err != nil || plaintext != "umami-secret" {
+		t.Fatalf("round trip failed: %q, %v", plaintext, err)
+	}
+	if _, err := second.DecryptSecret(ciphertext); err == nil {
+		t.Fatal("ciphertext decrypted with the wrong key")
+	}
+	cleared, err := first.EncryptSecret("")
+	if err != nil || cleared != "" {
+		t.Fatalf("empty secret should clear storage: %q, %v", cleared, err)
+	}
+}