Several list/search/Do-API request fields are parsed but silently ignored, so callers can't tell they didn't apply

A cluster of request fields on list, search and the Do API are accepted without error but then do nothing. Because there's no error and no warnings, a caller has no way to tell the field didn't apply — you just quietly get default behavior.

These bit me while wiring integrations. The ones I hit:

• inclFields on POST /-/v0/list — always forced to InclPageFields.Default.
• limit on list for Pages (hardcoded) and on search (never read). Only list-Events honors limit.
• sortOrder on list for Posts — ordering is hardcoded most-recent-first. (Pages and Events do honor it.)
• filter.isAuthorWaiting on list-Pages — parsed, filtering line commented out.
• defaultTopicType on category upsert-simple — hardcoded to Question.
• doWhy and top-level pretty on the Do API — parsed, never used.
• lookWhere.inCategories on list-Posts — resolved but the Posts query never uses it, so it does not restrict results.

This is an idea more than a bug report: even a warnings: [] field on responses (the internal /-/search already has one) would make all of these discoverable instead of silent no-ops.