aports: extract aw88261_acf.bin on-device instead of shipping it

New package fp6-vendor-blobs: a manifest-driven systemd oneshot that
copies proprietary blobs out of the stock Android partitions on first
boot. pmOS installs flash only boot+userdata, so every installed unit
still carries the stock vendor/dsp partitions - the device duplicates a
file it already contains, for its own operation, and nothing proprietary
is distributed by us. Partitions are mounted read-only (ext4 additionally
with noload - not even a journal replay touches the stock data), every
copy is sha256-pinned and a miss fails loudly, and the consuming devices
are unbound and re-probed afterwards so the feature works the same boot.

The rebind is unconditional by design: aw88261 binds on a bare i2c
chip-id probe and requests the ACF only at ASoC card init (~21 s, after
SoundWire enumeration), so a bound device can still be one that lost the
firmware race - and that failed request is never retried.

soc-fairphone-fp6-audio (pkgver 4) stops shipping the blob, installs the
manifest fragment instead, and re-runs the extractor from
post-install/post-upgrade so upgrades restore the file immediately (the
old package version removed it on upgrade). License drops back to plain
BSD-3-Clause - nothing proprietary left in the package.

Verified on the dev phone (fp6 repo journal/blobs/captures/
2026-08-24-first-boot-extractor-verification.txt): first-boot extraction
+ same-boot audio, mid-session post-upgrade recovery, and the everyday
fast-path no-op; committed files byte-identical to the tested deployment.

Assisted-by: Claude:claude-fable-5

aports/device/soc-fairphone-fp6-audio/soc-fairphone-fp6-audio.post-install

@@ -0,0 +1,6 @@
+#!/bin/sh
+# aw88261_acf.bin is not shipped - extract it from the stock vendor
+# partition right away rather than at the next boot. --if-device makes
+# this a quiet no-op inside build/CI chroots (the image's first boot
+# runs fp6-vendor-blobs.service instead).
+exec /usr/lib/fp6-vendor-blobs/extract --if-device