D3: oakdb+pg:// fully wired (shared sea-orm entities, BIGSERIAL DDL,
connect-probe instead of pool retry on dead servers); Storage/Backend=pg
+ Storage/PgUrl config; 13 OAK_TEST_PG_URL-gated PG tests (verified
against a Docker postgres:16), always-on clean-error tests otherwise.
D4: DaVinci-style project manager — list with derived stats, create/
rename/duplicate/delete (confirm)/import/export (native dialogs,
ove/otio/fcpxml), shown at startup and from the file menu; facade
oakengine_library_* exports (list/create/delete/rename/duplicate/
import/export + project_load_library that binds write-through);
save/save-as menu becomes 'export project file', open splits into
from-library/from-file; status bar shows library write state; storage
activates on app start and flushes on exit; spawn_modal reentrancy
fixed (window-callback path) with a doc note.
Also: the P1 audio test's environment probe was lost in the ffi purge;
restored on cpal (the output device is cpal now).
