Use relative URLs and fixed script names

The build is flat (pages, loader.js, terminal.js, logo.png) and only uses
relative URLs, so the site works wherever it is hosted, e.g. at
https://berlin.ccc.de/kik/.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

astro.config.mjs

@@ -1,6 +1,19 @@
 import { defineConfig } from 'astro/config';
 
 export default defineConfig({
-  build: { format: 'file' },
+  // Relative asset URLs, so the site works wherever it is hosted, e.g. https://berlin.ccc.de/kik/
+  build: { format: 'file', assetsPrefix: '.' },
   compressHTML: false,
+  vite: {
+    environments: {
+      client: {
+        build: {
+          rolldownOptions: {
+            // The page's script and the terminal it loads
+            output: { entryFileNames: 'loader.js', chunkFileNames: 'terminal.js' },
+          },
+        },
+      },
+    },
+  },
 });