Remove Gallus_Pub project and all related files

This commit deletes the entire `Gallus_Pub` directory, including its configuration, source files, and dependencies.

astro.config.mjs

@@ -0,0 +1,5 @@
+// @ts-check
+import { defineConfig } from 'astro/config';
+
+// https://astro.build/config
+export default defineConfig({});