docker: install alsa-sof-firmware so SOF blobs ship in initramfs

linux-firmware doesn't include intel/sof/*.ri or intel/sof-tplg/*.tplg
on Fedora — those live in the separate alsa-sof-firmware package.
Without it our docker-build.sh's bundling loop found an empty
/lib/firmware/intel/sof/ and shipped nothing. Verified by extracting
proud-pipit-branch's initramfs: no SOF firmware → kernel had SOF
drivers built-in but no DSP blob to upload → no audio card → audio_init
hits the no-card timeout and stalls.

Also: HP Chromebook 14 G7 (Drawcia / N4500 Jasper Lake) needs sof-jsl.ri
+ matching topology files which alsa-sof-firmware provides.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>