Add omacharts (#802)

A fast, keyboard-driven charting app for Omarchy, built on GTK4 and
libadwaita. It follows the active Omarchy theme, generates an indicator
palette for whichever theme is in force, and ships a plugin for the bar.

Source build from the project's own tagged release, tracked by a GitHub
watch so version bumps come from the release feed. Not in the AUR.

pkgbuilds/omacharts/.omarchy/package.json

@@ -0,0 +1,9 @@
+{
+  "source": "local",
+  "upstream": {
+    "watch": {
+      "github": "jorgemanrubia/omacharts",
+      "pattern": "v(?P<version>[0-9]+(?:\\.[0-9]+)*)"
+    }
+  }
+}