Register bool and duration ConfigSpec keys from the Default's type, move
fedwiki's four sync knobs and discourse's two into their integrations'
ConfigSpecs, and replace core's read of fedwiki-custom-domain-target
with a core domains-connect-target key resolved once and threaded
through server and worker config.
Generate init's optional-integration scaffold sections from each
registered ConfigSpec instead of the hand-maintained list, and reword
the Temporal boot warning generically.
Archives the integration-config-parity change; status bookkeeping and
the verify-skill doc follow with the test-stack commit.
