feat(validation): relax Instagram URL validation to support all content types

- Create validateInstagramUrl utility using URL constructor
- Replace regex-based validation with hostname and protocol checks
- Support posts, reels, IGTV, and URLs with query parameters
- Add comprehensive unit tests (22 tests, all passing)
- Add integration tests for new URL formats
- Update API documentation with supported URL formats

Closes: #RelaxInstagramUrlValidation

src/routes/api/queue/+server.ts

@@ -8,6 +8,7 @@
 
 import { json, error } from '@sveltejs/kit';
 import { queueManager } from '$lib/server/queue/QueueManager';
+import { validateInstagramUrl } from '$lib/server/validation/instagram-url';
 import type { RequestHandler } from './$types';
 
 /**
@@ -41,12 +42,10 @@ export const POST: RequestHandler = async ({ request }) => {
       return error(400, { message: 'URL is required and must be a string' });
     }
     
-    // Validate Instagram URL format
-    const instagramUrlPattern = /^https:\/\/(www\.)?instagram\.com\/p\/[a-zA-Z0-9_-]+\/?$/;
-    if (!instagramUrlPattern.test(url)) {
-      return error(400, { 
-        message: 'Invalid Instagram URL format. Expected: https://instagram.com/p/{post-id}' 
-      });
+    // Validate Instagram URL format using utility
+    const validation = validateInstagramUrl(url);
+    if (!validation.valid) {
+      return error(400, { message: validation.error || 'Invalid Instagram URL' });
     }
     
     // Enqueue the URL