Add the Discord community to the Learn menu

Every other pointer at the community lives in an error path or a doc, so
there was no way to reach it from the menu. Prefer the Discord app when
it is installed, and fall back to the invite in a browser when it is not.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

bin/omarchy-launch-discord-community

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# omarchy:summary=Open the Omarchy Discord community in the Discord app or a browser.
+
+invite="https://discord.gg/tXFUdasqhY"
+
+if omarchy-cmd-present discord; then
+  exec setsid uwsm-app -- discord --url -- "discord://-/invite/${invite##*/}"
+else
+  exec omarchy-launch-webapp "$invite"
+fi