Add optional Nanobot plugin controls (#4396)

* feat: add optional nanobot features

* test: update azure install hint expectation

* fix: validate optional feature extras

maintainer edit: verify requested dependency extras before treating optional features as installed, propagate restart state from feature enablement, and align docs with the new plugins enable command.

* fix: bound optional feature installs

maintainer edit: make optional feature installs time out as a normal install failure instead of leaving the WebUI or CLI action waiting indefinitely.

* feat: slim optional channel dependencies

* fix: log optional install commands

* fix(webui): gate remote feature installs

* docs: clarify webhook plugin example

* fix(webui): harden optional feature installs

* fix: install optional deps without package fallback

* fix(cli): refine plugin feature controls

* fix(webui): count enabled nanobot features

* fix(webui): allow slow feature install routes

* fix(webui): allow disabling websocket channel

* fix(plugins): simplify optional feature controls

* fix(webui): polish apps catalog states

* fix(webui): confirm nanobot support installs

* fix(webui): polish nanobot install dialog

* fix(webui): suppress empty websocket handshakes

* fix(webui): clarify apps plugin summary

* fix(webui): localize workspace access copy

* fix(plugins): polish optional feature controls (#4691)

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Co-authored-by: Xubin Ren <52506698+Re-bin@users.noreply.github.com>

docs/quick-start.md

@@ -329,7 +329,7 @@ nanobot --version
 If you use WhatsApp from a source checkout, keep the optional dependencies installed:
 
 ```bash
-python -m pip install -e ".[whatsapp]"
+nanobot plugins enable whatsapp
 ```
 
 ## First-Run Troubleshooting