Retire /people/:id/all_comments now that the combined feed replaces it

[maebeale]

🤖 From Claude: Filed as a follow-up to #2355.

What

/people/:id/all_comments is no longer linked from anywhere. #2355 added /people/:id/comments_and_communications — a superset that shows the same aggregated comments interleaved with the person's communications — and repointed every caller at it:

• the combined comments & communications section on the person, event registration, scholarship, story, and story idea forms
• topic_subscriptions/_form.html.erb
• continuing_education_registrations/edit.html.erb
• users/_form.html.erb

The old page is still reachable by typing the URL, but nothing navigates there.

Why it wasn't done in #2355

The instruction was to repoint the links, not to delete the page — and the two pages aren't quite identical, so retiring it is a judgement call worth making deliberately:

• The new page covers it. Both use PersonCommentAggregator, both have a composer with the same record picker, and the new one adds communications, more filters, and full-height bodies.
• What differs. all_comments edits a comment inline (comments/_aggregated_comment + comments/create.turbo_stream.erb prepending into the feed). The combined page is read-only per row — you click through to the record to edit. If inline editing matters, port it before deleting.

Scope if we retire it

• config/routes.rb — the get :all_comments member route
• PeopleController#all_comments and its entry in the set_person before_action
• app/views/people/all_comments.html.erb, app/views/people/person_comments_results.html.erb
• spec/requests/people_all_comments_spec.rb
• the "Aggregated comments for a person" entry in config/features.yml (or repoint its action_path at the new page)
• check whether comments/_feed and comments/_aggregated_comment still have callers — the global /comments index uses them, so they stay

Alternative

Keep it addressable and leave it unlinked. Cheap, but it becomes a second person-comments page that drifts.