`showChart` sometimes receives an encoded URL breaking the data fetch

**Describe the bug** As in the title, the `showChart` function sometimes receives a URL-encoded URL, which causes the fetch to fail as it tries to request the URL-encoded URL as relative to the current path. **To Reproduce** Steps to reproduce the behavior: 1. Go to a job 2. Click on 'Charts' 3. See 'Page not found.' errors **Screenshots** <img width="1489" height="299" alt="Image" src="https://github.com/user-attachments/assets/57e0f331-52d7-4339-a452-3d5a3660113e" /> <img width="852" height="802" alt="Image" src="https://github.com/user-attachments/assets/34e361d8-d407-4780-82f3-2acfebfc6d14" /> **Hydra Server:** - NixOS 25.11.20250814.fbcf476 - Hydra 0-unstable-2025-08-12 (using nix-2.29.1 and nix-eval-jobs-2.30.0)