Cody v0.50.0

Back up and flash Qualcomm devices in emergency download mode (EDL) from the tablet.

• Detects a Qualcomm device in emergency mode (USB 05c6:9008), reads its chip serial, hardware id and key hash, and sends the loader you choose after you confirm it.
• Reads the partition tables and storage size, checks that the tables fit the measured disk, and backs up any partition or the whole user area with checksums.
• Flash a partition from a file or erase one: Cody saves and verifies a copy first, writes in blocks you can cancel, reads back to verify, and says plainly when a write may have happened but could not be verified.
• Back up a whole unit as a set and restore it onto the same unit only (serial, key hash, storage and disk id must match), partition tables last.
• Start-up and identity partitions need an extra typed confirmation; the eMMC boot areas and RPMB are never written.
• Every copy that justifies a write is read twice and must match; reads that do not line up with what the device actually sent are refused.

Tested against a simulated device only; real-hardware checks are listed in docs/hardware-checklist.md.

Full Changelog: v0.49.0...v0.50.0