refactor(backend): extract to pkg/cap

internal/util/errs.go

@@ -7,12 +7,4 @@ const (
 	errCreateHTTPRequestFailed = "创建HTTP请求失败: %w"
 	errHTTPRequestFailed       = "请求%s接口失败: %w"
 	errInvalidCustomValue      = "invalid value: %v"
-	errInvalidSignKey          = "invalid sign key: %w"
-	errSignKeyLengthInvalid    = "sign key must be 32 bytes (64 hex characters)"
-	errCreateCipherFailed      = "failed to create cipher: %w"
-	errCreateGCMFailed         = "failed to create GCM: %w"
-	errGenerateNonceFailed     = "failed to generate nonce: %w"
-	errDecodeCiphertextFailed  = "failed to decode ciphertext: %w"
-	errCiphertextTooShort      = "ciphertext too short"
-	errDecryptFailed           = "failed to decrypt: %w"
 )