Move milkdrop-preset-converter-aws to devDependencies

The demo site still imports it, so it needs to remain as a dev
dependency for the Vite build. Consumers don't need it since it's
not used in the library bundle.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/webamp/package.json

@@ -73,6 +73,7 @@
   "homepage": "https://github.com/captbaritone/webamp/",
   "devDependencies": {
     "ani-cursor": "workspace:*",
+    "milkdrop-preset-converter-aws": "^0.1.6",
     "winamp-eqf": "workspace:*",
     "@babel/preset-env": "^7.25.0",
     "@rollup/plugin-babel": "^6.0.4",

pnpm-lock.yaml

@@ -474,6 +474,9 @@ importers:
       jest-puppeteer:
         specifier: ^10.0.1
         version: 10.0.1(puppeteer@22.6.2(bufferutil@4.0.8)(typescript@5.6.3)(utf-8-validate@5.0.10))(typescript@5.6.3)
+      milkdrop-preset-converter-aws:
+        specifier: ^0.1.6
+        version: 0.1.6
       postcss:
         specifier: ^8.4.21
         version: 8.5.6