1. Upgrades the pinned CPython version to 3.14.3t (free threaded).
2. Dependencies have been migrated, so Linux builds now run with free-threaded support.
3. Upgrades to support Flet 0.85.0.
4. An experimental fix to address HDR possibly being switched off on selecting a folder due to a Windows API bug: #216
5. Some minor warning fixes for build scripts.