FW16 (tulip): failed EPR transition leaves hard throttle asserted and latches the port until physical AC removal or EC Reboot #92

Both EPR failure handlers (EPR_MODE_ENTER_FAILED branch and the epr_flow_pending_deferred give-up) leave the transition throttle event set; clear_prochot() only releases it when AC power exceeds 100W, which cannot hold after a failed EPR entry. The epr_active = 0xff no-retry marker is cleared only on a port-disconnect response, so it survives missed disconnect events and PD controller resets (EC RAM re-imposes it onto freshly reset silicon — verified live). Result: system-wide slow state (BIOS included) and/or a port stuck attach-without-contract; only unplugging AC recovers.

Proposed minimal fix: #90
Full instrumented investigation + public telemetry: tyeth/framework-system#1 / https://github.com/tyeth/fw16-gpu-watchdog