Add a full/factory image download

It would be nice to add an option to download the "full" firmware image for ESP targets, similar to the "factory" image provided by Tasmota.

So the `bootloader.bin`, `boot_app0.bin`, `firmware.bin` and `partitions.bin` files, with the addresses used for flashing.

This would allow advanced users to flash the firmware manually.

Start by tracing the existing ESP firmware download flow and how target-specific flashing addresses are represented. Use the requested bootloader.bin, boot_app0.bin, firmware.bin, and partitions.bin artifacts as the acceptance checklist, and verify that the new full/factory option downloads all four with their addresses for manual flashing.

Written by the indexing model from the issue text.