* Update steam-runtime-tools; no practical effect on this branch (steamrt/tasks#766, steamrt/tasks#767)
### SDK
* Re-export 2048-bit signing key with a stronger self-signature. This ensures that the apt-secure(8) infrastructure will continue to treat it as valid in 2026 and beyond. (steamrt/tasks#751)
* Mark a newly-generated 4096-bit signing key as trusted, starting the process of key rotation to this new key. We will sign the apt repository with both keys for a while, and the old key can eventually be phased out. (steamrt/tasks#751)
* Add empty directories required by some Toolbx use-cases
* Add `flatpak-spawn` command to the `PATH`, required by some Toolbx use-cases