fix: resolve all lint errors across source and test files

- Fix unused function parameters (prefix with _)
- Fix unused imports in test files
- Fix import ordering in test files
- Auto-fix formatting issues across 22 files

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/client/components/ImageUpload.tsx

@@ -10,7 +10,11 @@ interface ImageUploadProps {
 const MAX_SIZE_BYTES = 5 * 1024 * 1024; // 5MB
 const ACCEPTED_TYPES = ["image/jpeg", "image/png", "image/webp"];
 
-export function ImageUpload({ value, imageUrl, onChange }: ImageUploadProps) {
+export function ImageUpload({
+	value: _value,
+	imageUrl,
+	onChange,
+}: ImageUploadProps) {
 	const [uploading, setUploading] = useState(false);
 	const [error, setError] = useState<string | null>(null);
 	const [localPreview, setLocalPreview] = useState<string | null>(null);