Spell perPage the same way in every paginated tool (#3142)

* Fix perPage parameter name in actions_list schema

The schema declared per_page while the handler reads pagination through
OptionalPaginationParams, which looks for perPage, so the value was
always dropped and perPage fell back to the default 30.

* fix(projects): spell the page size the way the rest of the server does

projects_list advertised per_page while every other paginated tool
advertises perPage. The handlers read per_page, so it worked, but it left
one tool spelling pagination differently from the other 30 and that is how
actions_list ended up advertising a name nothing read.

The schema now says perPage. per_page is still read when perPage is absent:
the projects tools have advertised it since September 2025 and clients
sending it get the size they ask for today.

TestAllToolInputSchemasUseCanonicalPaginationNames walks the whole tool
inventory and rejects case and underscore variants of page, perPage, after
and before. On main it fails on actions_list and projects_list.