fix: review fixes for step 4a

- e2e: the heap check uses a socket slot now, so it waits for the device
  to free it, and test_every_client_reconnecting_at_once closes its
  clients before the check runs.
- Comments and docs that still named removed things (the /controller read,
  the event buffer, memStatus, SocketEmitter, ModelSnapshot).
- ESPNetwork::emitSockets is emitStatus: one socket, and it sends the status.
- Unused includes, whitespace-only lines left by the toJSON removal.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

GLOSSARY.md

@@ -84,7 +84,7 @@ The seam through which a shade's behaviour reports what happened: changes for th
 
 **Entry point**
 Where a request from outside reaches the firmware: an HTTP route, an MQTT command topic or a frame received from a remote.
-_Avoid_: controller (it already names the owner of the shade list and the `/controller` read)
+_Avoid_: controller (it already names the owner of the shade list)
 
 **HttpRoutes**
 The HTTP routes on port 80: the web UI's files, login, the file transfers and the three commands for scripts. Everything else is an op on the socket.