feat(notforge): add Gitea API foundation

crates/notforge/src/error.rs

@@ -0,0 +1,36 @@
+use miette::Diagnostic;
+use thiserror::Error;
+
+/// Error type for forge lifecycle, API, git, and secret-resolution failures.
+#[derive(Debug, Diagnostic, Error)]
+pub enum NotforgeError {
+    /// Configuration could not be loaded or parsed.
+    #[error("configuration error: {0}")]
+    #[diagnostic(code(notforge::config))]
+    Config(String),
+
+    /// A required secret could not be resolved.
+    #[error("secret resolution error: {0}")]
+    #[diagnostic(code(notforge::secret))]
+    Secret(String),
+
+    /// Forge API communication failed.
+    #[error("HTTP error: {0}")]
+    #[diagnostic(code(notforge::http))]
+    Http(String),
+
+    /// A lifecycle command failed.
+    #[error("command error: {0}")]
+    #[diagnostic(code(notforge::command))]
+    Command(String),
+
+    /// A git operation failed.
+    #[error("git error: {0}")]
+    #[diagnostic(code(notforge::git))]
+    Git(String),
+
+    /// Repository lookup or provisioning failed.
+    #[error("repository error: {0}")]
+    #[diagnostic(code(notforge::repository))]
+    Repository(String),
+}