Repinned the server and api-go forks to the stream heads.

[moetemp]

This PR moves the server and api pins from the channel heads to the stream heads.

What changed?

• go.mod replaces go.temporal.io/server with github.com/moetemp/temporal at the top of the stream server chain.
• go.mod replaces go.temporal.io/api with github.com/moetemp/api-go at the stream api head.

Part of AI-198 (epic AI-37).

Why?

Nothing here is a feature. The stream commands in the next PR need the stream protos and a server that serves the stream service in start-dev. Both heads sit on top of the channel heads, so the channel commands keep the server they were written against. Go, nexus and the sdk don't move.

How did you test it?

Link to a test plan if any -

• Unit Tests
• Staging
• End to End Tests

go build ./... passes and go mod tidy leaves both modules as they are. The TestChannel unit tests and suite cases still pass on the new pins.

[moetemp]

Paused per the 2026-10-05 design review (the decision record is on the proposal page, section 14). Resumes in phase 2 with the CHASM notification work. The branch stays as a pin.