fix(server): wire Memory.node into the delivered httpapi app graph - #313

…ssue #311)

Memory.node appeared in every consumer's dependency array, but LayerNode
builds feed dependencies only to a node's own implementation body without
re-export — the ambient context delivered to live sessions is the mergeAll
of the app group's direct members at server.ts buildLayer call site, which
lacked Memory.node. All five serviceOption(Memory.Service) guards therefore
silently resolved None: /memory answered 'remains off' and memory_search
'Unabailable' despite a valid identity and init stamp.

Add Memory.node to the app group and export the app graph so the new
regression test builds the exact production delivery graph: one probe
asserts Memory.Service is reachable inside it, one drives the real /memory
command end-to-end. Reverting the wiring turns the test 0/2 with the
literal symptom.

Drop the retired V2 session vocabulary, point extenders at src/memory and
src/config references, and record the /dag-* command family, template
precedence, the /init memory-activation gate, and the release-notes
template requirement.