Findings: industry paradigm research (watchdog-retry is the norm,
mid-stream hedging has no public precedent; pi-tps threshold-based
stall deduction; Gregg off-CPU paired reporting; vLLM exclusion
clauses). Design: generation_ms redefined as net generation time
(wall minus all inter-chunk stalls over threshold), CallStats gains
stall_ms/stall_count, HEDGE__STALL_AFTER_S mid-stream hedge
independent of HEDGE__AFTER_S. Issues #27#28.
