TypedPython: chunked eval-breaker polling for range loops (#141 follow-up) #206

#141 phase 1 polls the eval breaker on every loop iteration through a register countdown, so fannkuch costs +8.2% against develop (median 1.082, range 1.043 to 1.191; with loop polls removed it is 1.000). The leader accepted this as the price of the fix.

Follow-up (b): for a ForRange loop the trip count is known, so split it into chunks of TP_POLL_INTERVAL iterations and poll once per chunk. break/continue must keep their meaning across the chunk loop. while loops keep the per-iteration countdown.

Done when: the eval-breaker tests stay green, a test shows KeyboardInterrupt still reaches a long range loop, and fannkuch and spectral-norm are re-measured (interleaved, quiet window).