Update image endpoint headers to implement aggressive cache-busting strategies, including `Cache-Control`, `Pragma`, `Expires`, `ETag`, and `Vary`, to ensure social media platforms always fetch the latest image version. Replit-Commit-Author: Agent Replit-Commit-Session-Id: 2cd2c0bc-434c-4bc9-ad3f-b99d3897a0d1 Replit-Commit-Checkpoint-Type: full_checkpoint Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/8cc42625-c1f5-4e43-99bd-77f2c4dedee2/2cd2c0bc-434c-4bc9-ad3f-b99d3897a0d1/gjpMN2A