[P2] Gateway route completion — 42 missing legs registered

Register every client-expected leg for storage / messaging / groups / licensing
/ events / indexer / oracle-feeds / compute-jobs / portfolio-performance so the
skeleton reaches a real endpoint instead of a 404. A single DRY _p2_route_specs()
table feeds both the live router and the batch dispatcher.

  - 5 WIRE routes run through the universal _call() seam (gate_action first):
      GET  /messaging/conversations            -> social.get_conversations
      GET  /messaging/conversations/{id}/messages -> social.get_messages
      POST /groups                             -> social.create_community
      POST /licensing/ip                       -> ip_royalties.register_ip
      POST /licensing/licenses                 -> ip_royalties.license_ip
    (added two thin flat delegators on SocialService so the nested XMTP reads
     are reachable through _call's flat getattr).
  - 37 routes have no backing service yet -> honest 501 not_implemented via a
    shared _not_impl() factory (never a fabricated 200).
  - Routes that already existed (oracle/price, portfolio/complete·positions·
    history, compute/store·ipfs·arweave, events/stream) are deliberately NOT
    re-registered — no collisions.

Regenerated docs/ROUTES.md (196 routes); the route-table doctor check is READY
and the staleness guard passes. Adds tests/test_p2_route_completion.py (43 tests:
WIRE 200s, honest 501s, pre-existing routes intact). Full suite 655 green.

Author: Neo