fix(drive): stop manual server scripts

[kitlangton]

Why

A manual script can intentionally launch only an isolated server and remain active for an external client. Even after that server is ready, Drive leaves the instance manifest in starting, so stop --name rejects it and the owner process must be terminated manually (#88).

What Changes

Treat a successful manual server.launch() as a script readiness boundary, just like tuis.launch(). Server-only scripts become inspectable and stoppable while their run Effect remains active; scripts that have launched neither a server nor a TUI remain protected as genuinely starting.

Scope

This only changes readiness publication for manual scripts. Server lifetime, control-socket ownership, automatic scripts, and TUI readiness are unchanged.

Verification

cd packages/drive
bun run check
bun run test

• 274 Effect tests pass.
• 60 CLI integration tests pass, including a new server-only Effect.never fixture that becomes ready and shuts down through stop --name.