Fix XC URL sub-path handling in profile refresh and EPG creation

- Fix credential extraction in get_transformed_credentials() using negative
  indices anchored to the known tail structure instead of hardcoded indices
  that break when server URLs contain sub-paths
- Fix EPG URL construction in M3U form to normalize server URL to origin
  before appending xmltv.php endpoint

XC accounts with sub-paths in their server URL (e.g., http://server.com/portal/a/) caused two failures: profile refresh extracted wrong credentials from the URL path due to hardcoded array indices, and EPG auto-creation appended xmltv.php under the sub-path instead of at the domain root. Both fixes normalize away the sub-path using the same approach the backend's XCClient already uses for API calls.

apps/m3u/tasks.py

@@ -2305,10 +2305,12 @@ def get_transformed_credentials(account, profile=None):
                 parsed_url = urllib.parse.urlparse(transformed_complete_url)
                 path_parts = [part for part in parsed_url.path.split('/') if part]
 
-                if len(path_parts) >= 2:
-                    # Extract username and password from path
-                    transformed_username = path_parts[1]
-                    transformed_password = path_parts[2]
+                if len(path_parts) >= 4 and path_parts[-1] == '1234.ts':
+                    # Extract username and password from the known structure:
+                    # .../{live}/{username}/{password}/1234.ts
+                    # Using negative indices so sub-paths in the server URL don't shift extraction
+                    transformed_username = path_parts[-3]
+                    transformed_password = path_parts[-2]
 
                     # Rebuild server URL without the username/password path
                     transformed_url = f"{parsed_url.scheme}://{parsed_url.netloc}"

frontend/src/components/forms/M3U.jsx

@@ -148,7 +148,7 @@ const M3U = ({
         API.addEPG({
           name: values.name,
           source_type: 'xmltv',
-          url: `${values.server_url}/xmltv.php?username=${values.username}&password=${values.password}`,
+          url: `${new URL(values.server_url).origin}/xmltv.php?username=${values.username}&password=${values.password}`,
           api_key: '',
           is_active: true,
           refresh_interval: 24,