Rename _protocol.hpp messaging files for the NATS world

The messaging headers generated per entity are named <entity>_protocol.hpp (e.g. currency_protocol.hpp, currency_market_tier_protocol.hpp), with an aggregator protocol.hpp. The "protocol" suffix is a holdover from the old binary-protocol era. Today these files just hold NATS request/response struct=s (each with a =nats_subject and a response_type) — there is no wire protocol to speak of. Reconsider the naming: either drop the _protocol postfix (e.g. <entity>_messages.hpp / <entity>_messaging.hpp, or fold into a messaging/ namespace that makes the suffix redundant) or confirm "protocol" still reads sensibly as "the NATS message contract" and keep it deliberately rather than by inertia.

Scope: the codegen protocol facet templates (ores.cpp.protocol.*), the output paths in the facet catalogue, the aggregator header, and every #include across api/core/qt/shell/http/cli. A rename touches a lot of includes, so it is best done as a mechanical codegen-driven sweep (regenerate + fix includes) rather than by hand.

Naming by inertia: the suffix describes a world (a hand-rolled binary protocol) that no longer exists. New contributors read "protocol" and look for serialization/framing that isn't there. Aligning the name with the NATS request/response reality (or consciously keeping it) removes that friction and is a good cleanup to fold into the broader codegen/messaging tidy-up.

• Generated headers: projects/ores.refdata/api/include/ores.refdata.api/messaging/<entity>_protocol.hpp and the aggregator messaging/protocol.hpp.
• Templates: projects/ores.codegen/library/templates/ores.cpp.protocol.*.org (the protocol facet).

• Commission: currency — surfaced while reconciling currency's messaging headers during the unified-model migration.