carlos / platform Public

docs: region HA stage B plan rev 5, build-ready consolidation

Fixes every pre-flight scan row (K1-K25) and lists each with its fix.
No task depends on a later one: the hostclaim probe-stop primitives
move into 8a, ErrLaterAttemptUnlaunchable and openRelocationStores to
where they are first used, and labels 8a-11 are kept. Rev 3 and rev 4
layers are folded into each task's text; every test and function has
a real body. C10's three-argument cleanup and
claimparticipation_completed.go are committed in Task 9 as region HA
code behind the activation gate. Each task was compiled and tested at
its own commit in a throwaway copy on top of internal/instancekey from
instance-key-build e8487c3a.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>