feat: v2 rewrite — hexagonal arch, ActivityPub federation, NATS, deployment-ready (#1)

crates/domain/src/errors.rs

@@ -0,0 +1,21 @@
+use thiserror::Error;
+
+#[derive(Debug, Error, Clone)]
+pub enum DomainError {
+    #[error("not found")]
+    NotFound,
+    #[error("unauthorized")]
+    Unauthorized,
+    #[error("forbidden")]
+    Forbidden,
+    #[error("conflict: {0}")]
+    Conflict(String),
+    #[error("unique violation on field: {field}")]
+    UniqueViolation { field: &'static str },
+    #[error("invalid input: {0}")]
+    InvalidInput(String),
+    #[error("external service error: {0}")]
+    ExternalService(String),
+    #[error("internal error: {0}")]
+    Internal(String),
+}