refactor: standardize error handling with exception.Builder

- Replace hardcoded error messages with structured error codes using exception.Builder.
- Introduce new common error constants in exception/common.go (CommonErrorInvalidInput, CommonErrorUserNotFound, etc.).
- Update exception/specific.go with domain-specific errors and remove redundant ones.
- Apply consistent error handling across auth, event, user services and middleware.

Co-authored-by: Gemini <gemini@google.com>
Signed-off-by: Noa Virellia <noa@requiem.garden>

exception/specific.go

@@ -2,4 +2,59 @@ package exception
 
 const (
 	ApiVersionNotFound = "00001"
+
+	// Auth Service
+	// Endpoint: AuthRedirectEndpoint (01)
+	AuthRedirectTokenInvalid   = "00001"
+	AuthRedirectClientNotFound = "00002"
+	AuthRedirectUriMismatch    = "00003"
+	AuthRedirectInvalidUri     = "00004"
+
+	// Endpoint: AuthMagicEndpoint (02)
+	AuthMagicTurnstileFailed    = "00001"
+	AuthMagicCodeGenFailed      = "00002"
+	AuthMagicInvalidExternalUrl = "00003"
+	AuthMagicInvalidEmailConfig = "00004"
+
+	// Endpoint: AuthTokenEndpoint (03)
+	AuthTokenInvalidToken = "00001"
+	AuthTokenGenFailed    = "00002"
+
+	// Endpoint: AuthRefreshEndpoint (04)
+	AuthRefreshInvalidToken = "00001"
+	AuthRefreshRenewFailed  = "00002"
+
+	// Endpoint: AuthExchangeEndpoint (05)
+	AuthExchangeGetUserIdFailed    = "00001"
+	AuthExchangeCodeGenFailed      = "00002"
+	AuthExchangeInvalidRedirectUri = "00003"
+
+	// Event Service
+	// Endpoint: EventInfoEndpoint (01)
+	EventInfoNotFound = "00001"
+
+	// Endpoint: EventCheckinEndpoint (02)
+	EventCheckinGenCodeFailed = "00001"
+
+	// Endpoint: EventCheckinQueryEndpoint (03)
+	EventCheckinQueryRecordNotFound = "00001"
+
+	// Endpoint: EventCheckinSubmitEndpoint (04)
+	// (None)
+
+	// User Service
+	// Endpoint: UserInfoEndpoint (01)
+	// (None)
+
+	// Endpoint: UserUpdateEndpoint (02)
+	// (None)
+
+	// Endpoint: UserListEndpoint (03)
+	UserListMeilisearchFailed = "00001"
+
+	// Endpoint: UserFullEndpoint (04)
+	// (None)
+
+	// Endpoint: UserCreateEndpoint (05)
+	// (None)
 )