Use Spoolman-based % calculation for RFID spools (same as manual)

Previously RFID slots used the hardware sensor percent from the WS
payload, which reflects RFID chip data rather than actual consumption.
Now both RFID and manual slots derive their percent from Spoolman
(remaining_weight / nominal_weight), keeping display consistent.

Also clears the percent cache on explicit RFID→other state transitions
so stale values don't persist after a spool swap.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>