livereload not (reliably) working with devcontainers that share the same uniform port configuration when forwarding ports to host

As a developer who uses devcontainers a lot I have to reuse the same devcontainer features sets as much as possible in order to avoid long devcontainer build times as well as storage explosion -- by sharing a uniform configuration of a single docsify server port instead of two (the second for livereload/hot reloading).

The problem is "a choice between the devil and the deep blue sea":
- either have a uniform docsify port configuration (such as 3300) across all my devcontainer configuration, as mandated by company policy, and have livereloading broken because the devcontainer's livereload port is never the same port number as the forwarded livereload port;
- or configure each and every devcontainer differently in order to use unique ports, which is not only cumbersome and error-prone, but blocked many times by company policies.

Please integrate the livereload port into a single contents+livereload notifications port. Other tools allow this for a long time. Thank you!

No files or tests are named. Trace the docsify CLI entry points that configure the docsify server, forwarded ports, and livereload notifications, then determine how a single shared port can serve both contents and reload events. Done means livereload works reliably when devcontainers forward one uniform port.

索引モデルが issue の本文から書いたものです。