Add cua-driver-bin, the Cua computer-use driver, to the fast ring

cua-driver ships prebuilt from the trycua/cua monorepo release feed. The
declarative github provider reads a release feed as a single product and
trips on the monorepo's foreign and hyphenated tags, so a bespoke
.omarchy/upstream.sh selects the newest stable cua-driver-rs release by
tag shape (upstream flags every driver release prerelease; nightlies are
distinguished by tag prefix instead) and reads its checksums.txt manifest.

The vendor tree stays together under /usr/lib/cua-driver with a /usr/bin
symlink, matching upstream's own layout: the CLI resolves its cursor-theme
compiler as a sibling of /proc/self/exe. Verified by installing the built
package into a clean archlinux:base container and exercising the CLI.

pkgbuilds/cua-driver-bin/.omarchy/package.json

@@ -0,0 +1,5 @@
+{
+  "source": "local",
+  "release_ring": "fast",
+  "min_release_age": "24h"
+}