Add bin/omarchy-install wrapper (shipped via omarchy-installer)

Brings back the omarchy-install command as a 5-line shell wrapper that
just exec's /usr/share/omarchy/install.sh. Not the 258-line Python
refactor-poc version — that one stays dropped.

The omarchy package keeps excluding bin/omarchy-install exactly so it
doesn't conflict with the omarchy-installer package's copy at /usr/bin.
All 25+ user-facing omarchy-install-* commands (gaming, browser, etc.)
still ship via omarchy.

bin/omarchy-install

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+# omarchy:summary=Run the Omarchy installer (shipped via omarchy-installer)
+# omarchy:group=install
+# omarchy:args=[install.sh args]
+
+exec bash "$OMARCHY_PATH/install.sh" "$@"