perf: optimize backend — HTTP client, DB queries, error handling, and config cleanup

src-tauri/src/error.rs

@@ -26,6 +26,15 @@ pub enum TuskError {
     #[error("Docker error: {0}")]
     Docker(String),
 
+    #[error("Configuration error: {0}")]
+    Config(String),
+
+    #[error("Validation error: {0}")]
+    Validation(String),
+
+    #[error("Export error: {0}")]
+    Export(String),
+
     #[error("{0}")]
     Custom(String),
 }