feat(core): add example plugin with declarative and imperative API examples

ticker.luau

@@ -0,0 +1,15 @@
+--!nonstrict
+-- Headless [[service]] entry: runs in the background with no UI, ticking once a
+-- second and publishing an incrementing counter to the plugin's shared state.
+-- Any of this plugin's entries (the hello widget) can read it with
+-- noctalia.state.get / noctalia.state.watch.
+
+local count = 0
+
+-- Drive this service's own tick rate
+noctalia.setUpdateInterval(1000)
+
+function update()
+  count += 1
+  noctalia.state.set("tick", count)
+end