pbl: add command flash log download and dehash tools

[asyba]

I added a new pbl command to get the logs from the flash region.
and then a script to deash them (using some other existing scripts) and be able to check the logs.

example:

(.venv) PebbleOS % pbl flash_logs --phone 192.168.1.101 --board asterix                         

Reading flash log region: 0x1FD0000 - 0x1FF0000 (128 KB)

Read 131072 bytes from flash
Saved flash logs to /PebbleOS/flash_logs_2026-01-01_22-03-35.bin

To parse and dehash the logs:
 tools/dehash_flash_logs.py flash_logs_2026-01-01_22-03-35.bin

(.venv) PebbleOS % tools/dehash_flash_logs.py flash_logs_2026-01-01_22-03-35.bin

Successfully parsed 1529 messages. Saved to: flash_logs_2026-01-01_22-03-35_parsed_2026-01-01_22-03-42.txt

? 14:13:49.000 unknown:0> Put bytes cleanup. Tok: 0
? 14:13:49.000 unknown:0> Encountered unknown attribute
? 14:13:49.000 unknown:0> ANCS MSG: Before record_app, app_id=<net.whatsapp.WhatsApp>, num_attrs=40, expiration=0
? 14:13:49.000 unknown:0> RECORD APP: Copying 40 existing attributes
? 14:13:49.000 unknown:0> RECORD APP: Copied AttributeIdMuteExpiration=0
? 14:13:49.000 unknown:0> RECORD APP: Preserving existing AttributeIdMuteExpiration=0