Handle ANSI warnings in config schema loader

[BRlin-o]

Issue

• Launching the app via MangaStudioMainRun.bat or python MangaStudioMain.py fails because ConfigLoader invokes manga_translator config-help, which prints ANSI-coloured warnings before the JSON schema. The raw json.loads call then raises and the UI initialization aborts with “Failed to load backend configuration schema.”
• Launching the app via MangaStudioMainRun.bat or python MangaStudioMain.py fails because ConfigLoader invokes manga_translator config-help, which prints ANSI-coloured warnings before the JSON schema. The raw json.loads call then raises and the UI initialization aborts with “Failed to load backend configuration schema.”

Environment

• Windows 11, NVIDIA RTX 3090
• Python 3.12.2 (project virtualenv).