2026.04.02

Unified the cover/hero image system into a single coherent pipeline. Cover images now use full URL paths as identifiers. Cover uploads are saved as exactly 500×500 (crop mode). Hero image displays as a square. Replaced 38 generic coveralt-XX.jpg filenames with descriptive names. Alt image pool is now read from disk at startup; homepage fetches the list dynamically. Audio clips moved to content/clips/, cover images to content/images/covers/.