stop() neither cancels nor waits for an in-flight MCPL inference/request #418

What's wrong

InferenceRouter doesn't pass an AbortSignal to membrane, and it keeps its stream in a local variable (main e6a0317). The framework's inference-request handler in src/framework.ts awaits the router without registering the operation anywhere stop() looks. stop() cancels and awaits agent streams only, then closes the MCPL servers.

Why it matters

After shutdown, the provider call keeps running, and keeps billing, until it finishes or times out. Its answer is then dropped on a closed connection. This is the cost of restarting a host while a server-initiated inference is running, and bounding it will matter more once #378's progress deadline lands.

How it was found

Codex flagged it while reviewing #380, and the reviewers confirmed it in source. #380 lists it as out of scope. It relates to #373 and #335 but is not covered by either.

Suggested fix

Track in-flight router inferences with an abort controller, and have stop() abort and await them before it closes the servers.

Found during our review of #380: #380 (review)

_{Posted by the maintainer's desk assistant.}