fix: serve buttplug locally in dev instead of Docker

Add a minimal Node.js static server (serve.mjs) to the buttplug package
that serves dist/ and wasm/ on port 8080 with correct MIME types.
Update dev:buttplug to use it instead of docker compose, avoiding a
full Rust/WASM Docker build on every dev start.

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

package.json

@@ -7,9 +7,10 @@
     "test": "echo \"Error: no test specified\" && exit 1",
     "build:frontend": "git pull && pnpm install && pnpm --filter @sexy.pivoine.art/frontend build",
     "build:backend": "git pull && pnpm install && pnpm --filter @sexy.pivoine.art/backend build",
+    "dev:buttplug": "pnpm --filter @sexy.pivoine.art/buttplug serve",
     "dev:data": "docker compose up -d postgres redis",
     "dev:backend": "pnpm --filter @sexy.pivoine.art/backend dev",
-    "dev": "pnpm dev:data && pnpm dev:backend & pnpm --filter @sexy.pivoine.art/frontend dev",
+    "dev": "pnpm dev:data && pnpm dev:backend & pnpm dev:buttplug & pnpm --filter @sexy.pivoine.art/frontend dev",
     "lint": "eslint .",
     "lint:fix": "eslint . --fix",
     "format": "prettier --write .",