Two follow-ups requested by the user (and the first flagged by the
reviewer for omission):
1) Different Minecraft versions or different packs leave behind mod jars
that crash Fabric on load. `downloadModsFolder` now removes the entire
`.mc_custom/mods/` directory before every install — including when the
pack is vanilla (no modsFolder) so leftovers from a previous modded
pack get cleared too.
2) `downloadMapZip` renames the single extracted top-level folder to the
pack name (sanitized for Windows: forbidden chars `<>:"/\|?*` and
control chars → `_`, trailing space/dot trimmed, reserved names like
CON/NUL prefixed, empty fallback to `map`). Collisions with user
worlds get `_2`, `_3` … suffixes so we never overwrite the user's
own worlds. The marker file tracks the post-rename folder so future
participant cleanup still removes only what the installer created.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>