check_cards: WRONG's remedy names only the card, but its figure is repeated in the MECHS block and on other pages

[realmarcin]

From the round-4 review of #212 (follows #240).

Where: scripts/fleet/check_cards.py main() closing line, and _fleet/README.md's WRONG bullet.

The WRONG remedy says to correct the card or figure_at_pin, with no refresh. A card figure is also copied to:

• the MECHS block's records: field in _fleet/fleet_fragment.html;
• index.md and resources.md, via step 6 of the update skill;
• the audit's card_records;
• the generated mechs.md.

Only card_records and mechs.md are checked. Fixing just the card leaves the graph panel and the home page contradicting /mechs/, with every gate green.

Fix:

• name every copy in the remedy, and say to rerun assemble_page.py;
• add a test that each MECHS records: equals its card.