chore(beads): track the spec.sr.ht issue backlog

Seven issues under the epic: Phases 3-5 (write plane -> review UI ->
deferred pile, chained by blocks), the loose-ends bucket of latent bugs,
and two ops tasks (nav restart, stale apk pins). Exported to a
git-tracked JSONL so the backlog is durable and portable, not only in the
local embedded Dolt DB.

bd init: initialize beads issue tracking