fix: remove hard-coded rollup-linux-x64-gnu dependency

The @rollup/rollup-linux-x64-gnu native binding was a hard dependency,
causing npm install to fail on arm64 and macOS platforms. Nothing in the
codebase uses rollup directly (build uses esbuild); rollup is only
pulled in transitively by @remotion/cli and manages its own
platform-specific bindings via its own optionalDependencies.

Closes #28

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

package-lock.json

@@ -17,7 +17,6 @@
         "@fastify/compress": "^8.3.1",
         "@fastify/cookie": "^11.0.2",
         "@fastify/static": "^8.0.0",
-        "@rollup/rollup-linux-x64-gnu": "^4.59.0",
         "chalk": "^5.3.0",
         "chokidar": "^3.6.0",
         "commander": "^12.1.0",
@@ -1623,7 +1622,9 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "license": "MIT",
+      "optional": true,
       "os": [
         "linux"
       ]