Card cleanup: drop Lumbridge branding and calendar-week checkpoints

Rename Karti-Small-RSI-3B to Karti-Small-Agent-3B

Name the six-tool surface, and replace the banner chart with the cycle ledger

Refresh the card to the current cycle: W36-W41 evidence trail, train/serve rendering-parity note, weights gated on promotion

Refresh the Karti model program