Three round-7 Copilot follow-ups on #19835:
- voice.record start handler used _load_cfg().get('voice', {}).get(...) without
shape checks, so malformed YAML (bool/scalar/list) returned 5025 instead of
using VAD defaults. Centralized _voice_cfg_dict() helper and type-guarded
silence_threshold/silence_duration with numeric fallbacks.
- TextInput pass-through check moved above paste/copy handling so configured
voice chords (ctrl+v / alt+v / cmd+v) beat the composer's paste/copy
defaults.
- parser now also rejects super+{c,d,l,v} — on macOS those are
copy/exit/clear/paste and would be advertised in /voice status but never
actually toggle recording.