Add Omarchy shell plugin for the Stream Deck

QML bar widget + popout panel (dev.woodard.streamdeck) that drives
streamdeck-ctl: key grid shaped by the connected model, per-key editor,
brightness slider, and daemon controls. Themed via qs.Commons.

Makefile gains build-ctl, install-ctl, install-plugin, validate-plugin
and uninstall-plugin targets.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BjuZBBfzXqZgxRhxzJvkkC

OMARCHY.md

@@ -6,6 +6,20 @@ privileged helper — see [README § Privileged commands](README.md)).
 
 ---
 
+## Shell plugin
+
+Beyond the key commands below, streamdeck-go ships an Omarchy **bar widget** that
+puts deck status, brightness, and inline key editing in the bar itself:
+
+```bash
+make install-plugin
+omarchy plugin enable dev.woodard.streamdeck right
+```
+
+See [omarchy-plugin/README.md](omarchy-plugin/README.md).
+
+---
+
 ## Terminal (Ghostty)
 
 ```yaml