fix: recap pagination broken for large lists

[anandgupta42]

Problem

Recap list pagination doesn't work properly when there is a large number of recaps:

1. TUI dialog hardcodes items.slice(0, 50) — can never see more than 50 recaps
2. CLI command has --limit but no --offset — no way to navigate past first page
3. listTraces() returns a flat array with no pagination support
4. Empty page (offset past end) shows misleading "No recaps found" message

Expected Behavior

• Users can paginate through all recaps via CLI --offset/--limit
• TUI dialog shows a reasonable number of recaps with scrolling
• Footer shows "Showing X-Y of N" with next-page hint
• Empty pages clearly indicate offset past end, not "no recaps"