Update particle background to increase particle spawn rate on mouse move, add ambient particle spawning when idle, and increase max particle limit. Replit-Commit-Author: Agent Replit-Commit-Session-Id: beb495f8-3942-42fd-9d1b-db8f707d320f Replit-Commit-Checkpoint-Type: full_checkpoint Replit-Commit-Event-Id: c2b88424-5180-488e-b61b-c1eb8bc69a5c Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/804258ec-282b-434a-9b89-a7ccc1690e42/beb495f8-3942-42fd-9d1b-db8f707d320f/3Fb2Xuc Replit-Helium-Checkpoint-Created: true