Add role, facilitator/membership status, age range, topic & staff-tag filters to the people directory

[maebeale]

🤖 suggested review level: 3 Read 📖 filter scopes wired through one dispatcher per dropdown; model + request specs cover each branch

Adds several filters to the people directory, built on the event-registration filter mechanism (shared events/_filter_select partial + collection Stimulus controller — no new JS). Rebased on main, so it also carries in and integrates the staff-tag filter from #2313.

General filter (everyone who can reach the index)

• Age range — dropdown of published AgeRange categories; matches people tagged with that range.

Admin-only filters (grouped in a blue panel)

• Role — story / blog / workshop / workshop-variation / workshop-log authors, and sector leaders.
• Facilitator status — active, inactive, boomerang (2+ facilitator affiliations, 1+ active), formerly active.
• Membership status — active/inactive (membership cancelled_at) and paid/due/overdue (current invoice vs. allocations + grace period).
• Topic subscription — people with an active (not unsubscribed) subscription.
• Staff tag — from Add StaffTags: internal admin-only tagging for people #2313 (staff_tagged_with); moved into this blue panel and restyled to match, gated by allowed_to?(:index?, StaffTag).

Field order

Name/email/phone → Organization → Sector name → Age range, then the blue admin panel (Role → Facilitator status → Membership status → Topic subscription → Staff tag), then Clear.

Notes

• The old "Sector leaders only" checkbox is folded into the Role dropdown.
• Workshop log authorship: WorkshopLog has no Person column — only created_by → User. So "workshop log author" = the person whose linked user created the log (routed through User). Flagging in case a different tie is intended.
• All filters flow through Person.search_by_params; no controller/strong-params change. New scopes return plain relations (where(id: subquery)) so count/paginate are unaffected.
• Blue is the admin/status marker here (matches the bg-blue-100 admin convention), not a DomainTheme color.
• Branch squashed to one commit and rebased onto main; updated the Features & tips seed.

Closes #2322