TimothyFran/OtamaticClient ? reverse-engineered prompt

Build me an ESP32 Arduino library that handles automatic OTA firmware updates from a remote server.

I want it to work with any Arduino network client, so it can run over WiFi, Ethernet, or GSM, and it should support both HTTP and HTTPS depending on the client I pass in. The device should check for a new firmware version on a schedule, download it if there is one, verify the download with SHA 256, and install it automatically with a reboot when finished.

Please also add optional signature verification with ECDSA P 256, rollback protection with a check after reboot, and an event based API so I can react to update status changes. It would be great if there is also a local browser update page for manual firmware uploads.

Include a few simple examples for basic WiFi use, signature verification, manual update control, and the local portal. If you need to, look up the current Arduino and ESP32 docs online while implementing it.