fix: address five latent issues and remove stale BUG test comments

[deer]

Seven test methods carried BUG: javadoc paragraphs documenting issues that had already been fixed in the source. Those paragraphs (and associated stale inline comments) have been removed. The tests themselves are unchanged and continue to pass.

Five fixes

• JsonNodeInputStreamProcessor — log all three previously silent throwables via JUL instead of swallowing them.
• LocalJDKLauncher — cache the SpawnAgent archive path in a static AtomicReference so createArchive() is called at most once per JVM rather than on every launch.
• AbstractTemplatedPlatform.close() — actually close the internal Server. Previously a no-op, leaving the bound port open indefinitely.
• AbstractTemplatedLauncher — log ClassNotFoundException during Iterable injection resolution instead of silently swallowing it.
• KillContainer + new KillSignal option — add the signal query parameter to the Docker kill request. Defaults to SIGKILL (matching Docker's own default), configurable via the new KillSignal option type.

New tests: LocalMachineCloseTests (fix 3), KillContainerRequestTests (fix 5).