feat: complete JjLib describe implementation

src/error.rs

@@ -56,3 +56,27 @@ impl From<jj_lib::config::ConfigGetError> for Error {
         Self::FailedReadingConfig
     }
 }
+
+impl From<jj_lib::repo::RepoLoaderError> for Error {
+    fn from(error: jj_lib::repo::RepoLoaderError) -> Self {
+        Self::JjOperation {
+            context: format!("Failed to load repository: {}", error),
+        }
+    }
+}
+
+impl From<jj_lib::backend::BackendError> for Error {
+    fn from(error: jj_lib::backend::BackendError) -> Self {
+        Self::JjOperation {
+            context: format!("Backend operation failed: {}", error),
+        }
+    }
+}
+
+impl From<jj_lib::transaction::TransactionCommitError> for Error {
+    fn from(error: jj_lib::transaction::TransactionCommitError) -> Self {
+        Self::JjOperation {
+            context: format!("Transaction commit failed: {}", error),
+        }
+    }
+}