Adds payout configuration fields (percentage/hourly + per-session
expense allowance) with a live payout preview to the class form,
a new Financial Reports page (per-class and date-range/monthly tabs,
per-session drill-down dialog) with reusable stat cards, and an
Institutional Expenses management page. Registers routes, sidebar
navigation, and permission constants for the new financial_reports
and expenses permissions.
kavehhn