Proxy: preview-path proxy substitution (global UseProxyMedia AND
per-footage enabled AND on-disk ready; export always uses originals),
proxy generate/delete/reveal/enable actions, ProxyDialog with global
and per-footage custom params, Tools menu + context-menu Proxy
submenus, progress in the status bar, OVE serialization of proxy
metadata and source_start_time.
Sync: timeline context-menu Synchronize by Source Time / by Waveform /
by Waveform (Adjust Speed) with ctrl-shift-w, cache-envelope
extraction with validity masks, reference/anchor selection and
single multi-undo application (replace-with-gap, speed adjust,
re-place) mirroring timelinewidget.cpp semantics.
Mike-Solar
f2af92958a