A route keeps serving after its owner is killed

Written by an AI agent (Claude) on behalf of @jasonkuhrt.

When a route's owner is killed (kill -9, or its parent dies) without touching routes.json, its hostname keeps forwarding to the old port:

$ portless myapp node server.js
$ curl myapp.localhost          # 200
$ kill -9 <portless pid>        # the dev server survives
$ curl myapp.localhost          # still 200, from the orphaned server

The daemon serves its cached routes until the file changes (startProxyServer in cli.ts), and RouteStore.loadRoutes drops dead owners only while loading. After a normal exit the same request is a 404.

#383 prunes the file on a timer. This is about the lookup itself skipping a dead owner, so the 404 comes at once and nothing is written.