Upload and view attachments behind a firewall

Factory networks behind strict proxies had to whitelist third-party storage domains to use run attachments; every attachment URL now stays on TofuPilot domains.

• Added attachments.tofupilot.app: uploads and downloads from SDKs, stations, and the dashboard no longer touch external storage hosts
• Added a 95 MB per-attachment limit with a clear error message, replacing an undocumented unlimited behavior
• Improved attachment serving with video seeking support and stricter content-type protections