chore: fix lint errors and reduce warnings across codebase (#234)

* chore: fix lint errors and reduce warnings across codebase

- Fix noExplicitAny catches in backend routes and plugins
- Fix noNestedTernary issues in backend services
- Add keyboard event handlers for useKeyWithClickEvents in frontend
- Disable noImportantStyles rule in biome.json
- Fix formatting errors across all changed files
- Fix test file lint issues

Closes #233

* fix: restore any types in test files for TS compatibility

* fix: revert Auth.tsx dependency array changes that caused infinite re-render

* fix: null-safe user.username access in AppContext dependency array

frontend/src/components/AboutModal.tsx

@@ -51,8 +51,18 @@ export default function AboutModal({ isOpen, onClose }: AboutModalProps) {
 	if (!isOpen) return null;
 
 	return (
-		<div className="modal-overlay" onClick={onClose}>
-			<div className="modal-content about-modal" onClick={(e) => e.stopPropagation()}>
+		<div
+			className="modal-overlay"
+			onClick={onClose}
+			onKeyDown={(e) => {
+				if (e.key === "Escape") onClose();
+			}}
+		>
+			<div
+				className="modal-content about-modal"
+				onClick={(e) => e.stopPropagation()}
+				onKeyDown={(e) => e.stopPropagation()}
+			>
 				<button className="modal-close" onClick={onClose}>
 					×
 				</button>