[moetemp]

What changed?

This PR removes the Workflow write path that S108 replaced.
Removed: BufferWorkflowCalls, FlushRunBuffer and DrainCloses with their messages (BufferWorkflowCallsRequest/Response, WorkflowCall, FlushRunBufferRequest/Response, DrainClosesRequest/Response). Also gone are the run buffer and the Workflow Task interceptor in workflow.rs, and the deferred withdrawal of the batch before a Local Activity (Withdrawal.defer and the Lua * key). The metrics that only these kept go too, as do the Workflow and Core mock-Worker tests.
The extension no longer gives Core a Workflow Task interceptor, and it has no sync calls. The service still refuses a Workflow-kind Producer, since a Workflow writes with its Local Activity's Producer. Safety TTL and the Workflow withdrawal rule in Lua stay, because the service create with an owner and an append with Workflow facts still use them.

Why?

Decision S108. A Workflow makes each create, publish and close from a Local Activity on the service calls. sdk-python p30 is green without these calls.

How did you test it?

cargo fmt --all -- --check, cargo clippy --workspace --tests -- -D warnings (also with --no-default-features --features tls-aws-lc), and STREAMS_REQUIRE=redis cargo test --workspace on standalone Redis, cluster Redis and memory. The capability tests now check the service create with an owner (safety_ttl) and with withdraw_run (run_fence).

[moetemp]

Closing as stale. This layer is folded into the v5 tip, #41, and the upstream review uses a fresh series instead. Plan: https://www.notion.so/4048fc567738814990b7c796ac28fe3f