v0.2.6

fix: increase frame pool from 3 to 5 slots to prevent exhaustion

A concurrent GET / snapshot holds a pool ref while sending ~150KB over
HTTP. Combined with a worker mid-send on the previous frame, all 3 slots
could be occupied simultaneously, stalling the broadcaster for up to 5s
and triggering Frigate's 20s ffmpeg watchdog.

5 slots (2.5MB PSRAM) eliminates the exhaustion window: snapshot(1) +
worker(1) + broadcaster(1) still leaves 2 free slots.

Also adds check_fw.sh utility script and removes stale coredump.elf.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>