User feedback: 'na refren ne pred na začetek refrena' — the clip should
start right when the chorus begins, not 0.3s before.
Changes:
1. Prompt rule: 'Začetek = TOČNO ko prva beseda refrena začne'
(was: '~0.3s PRED prvo besedo refrena')
2. Word-level extension: removed -0.15s buffer when extending back
(now lands exactly on word start)
Reasoning: with no_subs as default, we don't need buffer to avoid
cutting first word during fade-in (fade-in is now 0.05s = imperceptible).
Cleaner cuts directly at chorus onset.
sebastjan
ab5424d37b