EventProgramStatusReport: wire up or drop the unused featured_year/prior_year API

🤖 From Claude:

Found while reviewing the org affiliation / program-status branch (maebeale/remove-org-status-columns).

EventProgramStatusReport mirrors its sibling reports' period API, but nothing reads it:

• #featured_year, #prior_year, #all_trainings_group, #years_by_value have no callers.
• EventsController#program_statuses passes featured_year: selected_year, which therefore goes nowhere.
• events/program_statuses.html.erb and _program_status_report.html.erb read years plus the Aggregates sums; the hub card uses period_scope.

Two ways out:

• Wire it up — add a KPI strip to program_statuses.html.erb the way participation.html.erb and revenue.html.erb use featured_year / prior_year for year-over-year deltas. Probably the intent, and it's the figure annual reporting wants.
• Drop it — delete the four methods and the featured_year: constructor argument, keeping period_scope (which the reports hub does use).

Not urgent; no user-visible effect either way.

Start with EventProgramStatusReport and trace the featured_year argument from EventsController#program_statuses into events/program_statuses.html.erb and _program_status_report.html.erb. Compare the usage in participation.html.erb and revenue.html.erb before choosing whether to add the KPI strip or remove the unused API. Done means the selected direction is implemented consistently and no unused interface remains.