- strip QAbstractItemModel/QAction/signals-slots from UndoStack (UI
concerns belong to the app layer), index_changed becomes a
std::function callback
- decouple UndoCommand from Project via an optional modified-flag
callback pair
- add pure C ABI in include/undo + src/undo/c_api (oakundo_ prefix,
vtable-based command wrapper, OAKUNDO_E_* error codes)
- fix three engine-side defects: jump(0) infinite loop,
MultiUndoCommand child leak, push_pre_executed not undoable
- add gtest suites (22 cases) and a standalone build driver
- de-Qt all classes under src/common (std::string/vector/mutex,
std::filesystem, expat-based XmlStreamReader/Writer)
- add pure C ABI in include/common + src/common/c_api: opaque handles,
init returns NULL on failure, free(NULL) is a no-op, out-params with
negative OAKCOMMON_E_* error codes (include/common/error.h)
- remove single-consumer classes from oakcommon (html, jobtime,
otioutils, playbackaudioclock, tohex, util, avframeptr,
crashpadinterface/crashpadutils, autoscroll, digit, range); their
destinations are recorded in docs/zh/plans/riir/notes.md
- add gtest suites under src/common/tests (127 cases), standalone
build driver in src/common/standalone