Drop dead tables: jobs, courses, course_tutors, course_invitations #3020

Problem

Four tables survive from removed features:

• jobs (21 columns, 164 production rows) — the job board. All of it (model, controllers, mailer, policies, presenters, views, routes) was removed in f25f10b8 (2022-07-22, "remove job board code").
• courses, course_invitations, course_tutors (14 + 8 + 4 columns; 6 + 1755 + 7 production rows) — the deprecated Course feature. All code was removed in 4fb0f938 (2022-04-12, "Deletes deprecated Course code from codebase").

No model classes exist for any of them, and no code, template, locale file, or migration references the table names. The 2026 applications never touch them.

Proposed change

One migration:

safety_assured do
  drop_table :course_tutors
  drop_table :course_invitations
  drop_table :courses
  drop_table :jobs
end

Plus regenerate schema.rb. No ignored_columns step is needed: no release in git history references these tables, so nothing can break when they vanish. The production dump shows no foreign keys, views, or triggers on them.

Acceptance

• Tables and their indexes gone from schema.rb; full suite passes.
• Production deploy succeeds; no ActiveRecord errors in the drain afterwards.

Labels: refactoring, trivial