fix(installer): remove pre-v6.2.0 wrapper skills on update (closes #2309) (#2315)

Adds 32 entries to removals.txt covering the module-prefixed wrapper
skill names used pre-v6.2.0 (bmad-bmm-* and bmad-agent-bmm-*). Users
upgrading from v6.0.x / v6.1.x had these installed in their IDE skill
directories, but the v6.2.0 architecture switch dropped the module
prefix and the cleanup never knew the old names. Stale wrappers stayed
behind alongside the new self-contained skills, causing duplicates and
broken-file errors when invoked (referenced files no longer exist).

The removals.txt entries get added to the cleanup removalSet on every
install/update, so the next install run for an upgrading user removes
the stale wrappers automatically.