Remove or wire PublishRequest into an RPC

[lanycrost]

Problem statement

PublishRequest is defined in transport.proto with full structure (oneof frame, metadata, payload, inputs, transports, envelope) but is not referenced by any service RPC. It exists in all generated bindings (Go, TypeScript, Python), polluting the API surface and confusing SDK developers who discover the type and assume it's usable.

Proposed change

One of:

1. Remove it if it was speculative and no pub/sub RPC is planned near-term.
2. Wire it into a new RPC if pub/sub delivery is on the roadmap:

   service TransportConnectorService {
     // ... existing RPCs
     rpc Publish(stream PublishRequest) returns (stream PublishResponse);
   }

3. Mark deprecated if removal is planned but not immediate:

   message PublishRequest {
     option deprecated = true;
     // ...
   }

Affected area

• Proto definitions
• Generated bindings (will change automatically)

Compatibility / migration

Removing the message is a breaking change for any code that references PublishRequest by name. Check downstream repos (core, bobrapet, bobravoz-grpc, bubu-sdk-go) for imports before removing.

Additional context

Identified during architectural review. Dead contract surface in a foundational layer creates confusion across all SDK languages and bloats generated bindings.

[lanycrost]

Not implemented in commit 08327cf19369d0a8100c81779f2694d0f0029caa.

The current branch feature/tractatus-buf-validate leaves PublishRequest in place because downstream SDK conversion code still uses this shape. The tractatus-first path should either document PublishRequest as the canonical internal publish/conversion shape or add an additive RPC that uses it, then migrate consumers before any removal.

Leaving this issue open for a dedicated staged ABI decision.

[lanycrost]

Update: the branch was amended to remove local AI prompt files from the pushed commit. Current branch feature/tractatus-buf-validate points to commit 8bf4c4e21b50574bfd34e76fae8a5717d4a67897. Previous references to 08327cf should be treated as superseded by this amended commit.