Add detailed logging to mobile share/download flow

Debug why download button does nothing on mobile - logs will show:
- canShare detection results
- blob fetch status
- navigator.share() calls and errors

Author: willuhmjs

src/lib/utils/download.ts

@@ -14,14 +14,28 @@ export async function downloadOrShare(fileId: string, filename?: string): Promis
 	const fileUrl = `/api/files/${fileId}`;
 
 	// Desktop or no Share API support → traditional download
-	const canShare = isMobileDevice() && navigator.canShare?.({ files: [new File([], 'test')] });
+	const isMobile = isMobileDevice();
+	const hasCanShare = typeof navigator.canShare === 'function';
+	const canShare = isMobile && hasCanShare && navigator.canShare({ files: [new File([], 'test')] });
+
+	console.log('[downloadOrShare]', {
+		fileId,
+		filename,
+		isMobile,
+		hasCanShare,
+		canShare,
+		userAgent: navigator.userAgent
+	});
+
 	if (!canShare) {
+		console.log('[downloadOrShare] Using window.open fallback');
 		window.open(fileUrl, '_blank');
 		return;
 	}
 
 	// Mobile with Share API → fetch blob and share
 	try {
+		console.log('[downloadOrShare] Fetching blob from', fileUrl);
 		const response = await fetch(fileUrl);
 		if (!response.ok) {
 			throw new Error(`HTTP ${response.status}: ${response.statusText}`);
@@ -30,18 +44,30 @@ export async function downloadOrShare(fileId: string, filename?: string): Promis
 		const blob = await response.blob();
 		const file = new File([blob], filename || 'download', { type: blob.type });
 
+		console.log('[downloadOrShare] Calling navigator.share with file:', {
+			name: file.name,
+			type: file.type,
+			size: file.size
+		});
+
 		await navigator.share({ files: [file] });
+		console.log('[downloadOrShare] Share succeeded');
 		// Success: user shared or saved (no toast needed, native UI provides feedback)
 	} catch (error: any) {
+		console.error('[downloadOrShare] Share failed:', error);
+
 		// User cancelled the share sheet → AbortError (don't show error)
-		if (error.name === 'AbortError') return;
+		if (error.name === 'AbortError') {
+			console.log('[downloadOrShare] User cancelled share sheet');
+			return;
+		}
 
 		// Actual error → show toast with details
-		console.error('Share failed:', error);
 		const message = error.message || 'Unknown error';
 		addToast('error', `Failed to share file: ${message}`);
 
 		// Fallback: try traditional download
+		console.log('[downloadOrShare] Falling back to window.open');
 		window.open(fileUrl, '_blank');
 	}
 }