Enforce full Top-5 card format for sg-carmart outputs

[irfanzs]

Summary

• enforce full Top-5 card structure for sg-carmart results whenever cars are returned
• require complete per-car details including monthly breakdown, risk flags, trust signals, and negotiation checklist
• require at least 3 embedded images per returned car when available
• require explicit unavailable slot markers when fewer than 5 cars match constraints

Notes

• keeps concise output only for cases where user explicitly requests brief mode