[Development report #49] Audio Stack Improvements

virtual_oss: Do not build if WITHOUT_CUSE is set:
https://cgit.freebsd.org/src/commit/?id=f040ee6e407832fc9f08d85cd792d1cfb8104976

	- Fixes PR 289920:
	  https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=289920

devd: Remove SND package:
https://cgit.freebsd.org/src/commit/?id=5cc36854ee63dc695d90a841d9db587bec67ba24

MFCs to stable/15:

	- virtual_oss: Port to base:
	  https://cgit.freebsd.org/src/commit/?h=stable/15&id=5a31c623143f4a20e5b5fb337ec97ac0b39635fc
		- Squashed all follow-up fixes into this commit.
		- Bumped __FreeBSD_version.
	- mixer(8): Update virtual_oss path:
	  https://cgit.freebsd.org/src/commit/?h=stable/15&id=1cde8b0a257afbf2da74877b5130bdab50d42917
	- snd_hda: Implement automatic redirection between associations:
	  https://cgit.freebsd.org/src/commit/?h=stable/15&id=57327328f141bcdb6dbb81f0cd456eeca2080f43
	- Updated
	  https://wiki.freebsd.org/Releng/15.0ISSUES

audio/virtual_oss_sndio: New port:
https://cgit.freebsd.org/ports/commit/?id=a9bbba1949a79c419d88e64a280e56c0cc8131fc

audio/virtual_oss_equalizer: New port:
https://cgit.freebsd.org/ports/commit/?id=35215c174c450b6e7dfd2490334f7887b7c24710

audio/virtual_oss_bluetooth: New port:
https://cgit.freebsd.org/ports/commit/?id=2dcc66e8c6c4b92a3278ea874b41e4b81ae441ed

audio/virtual_oss: Ignore FreeBSD 15:
https://cgit.freebsd.org/ports/commit/?id=9b26d309123abf0e90651298b131783ba7d9b945

audio/virtual_oss_ctl: Do not depend on audio/virtual_oss after 1500066:
https://cgit.freebsd.org/ports/commit/?id=05b748dac1da72516797488219a94dd6f88ebd7f

packages: Add a sound package:
https://reviews.freebsd.org/D52823

HEADS-UP: virtual_oss in base:
https://lists.freebsd.org/archives/freebsd-stable/2025-September/003305.html

Bug triaging.

Helped Goran Mekić <meka@tilda.center> start adding kqueue(2) support to
sound(4). I will be reviewing his patches once in working state.

Working on Journal audio article.

This work is sponsored by the FreeBSD Foundation.

Christos