- new facade API: video stream overrides (colorspace/range/interlacing/
premultiply), pixel aspect, image-sequence params, stream enable,
source start time, and colorspace candidates - all undoable
- project explorer proxy actions now run through FacadeProxyTask and
the facade media-management functions (ProxyManager references in
projectexplorer.cpp drop from 5 call sites to a comment)
- footage properties dialog reads/writes through the facade; its two
app-side undo command classes are gone
- handle-model fix: the footage handle is a heap state object, not a
plain pointer cast - oakengine_footage_borrow() wraps app-held
Footage nodes correctly (nine UB reinterpret_casts caught by the
DialogFootageProperties tests)