Add page-size selector and jump-to-page pagination

[olsonjp]

Problem

215 pages × 50 per page is hostile to navigation. No jump-to-page, no page-size selector, no "Previous" affordance visible.

Solution

• Page-size selector (50 / 100 / 250)
• "Page X of Y" display with jump-to input
• Or: migrate to keyset/cursor pagination with infinite scroll within filters

Priority

P1