Make the skills --verify catalog budget configurable

[cliffhall]

Follow-up from the review of #2293 (which closes #2248). See PR thread for this review comment.

[cliffhall]

Triage: Priority Low (total 5)

• Severity 2 — minor friction: the catalog budget is hard-coded, and the workaround is editing the constant
• Urgency 2 — a follow-up from the feat: Skills extension phase 3 — CLI methods, TUI pane, resources/directory/read, and the frontmatter cross-check #2293 review; nothing waits on it
• Bonuses: +1 already milestoned (v2.7.0)

Board: #28, Status Todo (milestone already set; card was missing).