Seed the editor from Storage::load at boot and persist on :w/:sync
through Storage::save. A missing card/repo/unreadable note halts boot
with the reason on the panel rather than starting empty and clobbering
the note on the next save. Save errors are logged, buffer kept in RAM.
The git-push half of :sync stays a TODO — it needs git_sync graduated
into a module on the dedicated git thread; :sync saves for now.
637fe4a4f4