feat(shared-uload): add shared package with ShareModal and cross-app link creation

Provides ShareModal component and initSharedUload/createShortLink utilities
for other apps to create uLoad short links with source tracking.

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

packages/shared-uload/src/utils.ts

@@ -0,0 +1,29 @@
+export const QR_API = 'https://api.qrserver.com/v1/create-qr-code';
+
+export function generateShortCode(length = 6): string {
+	const chars = 'abcdefghijklmnopqrstuvwxyz0123456789';
+	let code = '';
+	for (let i = 0; i < length; i++) {
+		code += chars[Math.floor(Math.random() * chars.length)];
+	}
+	return code;
+}
+
+export function getQrCodeUrl(shortUrl: string, size = 400): string {
+	return `${QR_API}/?size=${size}x${size}&data=${encodeURIComponent(shortUrl)}`;
+}
+
+export function getShortUrl(shortCode: string, baseUrl?: string): string {
+	const base =
+		baseUrl || (typeof window !== 'undefined' ? window.location.origin : 'https://ulo.ad');
+	return `${base}/${shortCode}`;
+}
+
+export function downloadQrCode(shortCode: string, baseUrl?: string): void {
+	const shortUrl = getShortUrl(shortCode, baseUrl);
+	const url = getQrCodeUrl(shortUrl, 400);
+	const a = document.createElement('a');
+	a.href = url;
+	a.download = `qr-${shortCode}.png`;
+	a.click();
+}