Let the release script write the release commit it was never trusted with

Every release commit in the history reads `Release X.Y.Z` and none of them
carries the message this script would have written, so nobody has ever
passed it `--commit` — and the reason is in the message it wrote: a
Co-Authored-By trailer naming an assistant, which no commit in this repository
carries and none should.

The trailer goes, and so does the paragraph above it: the script's own header
already says why it exists, and a release commit is the one place a one-line
subject is the whole convention.

tools/set-version.sh

@@ -98,13 +98,7 @@ if [[ "${COMMIT}" == "1" ]]; then
     if git diff --cached --quiet; then
         echo "==> nothing changed; no commit made"
     else
-        git commit -q -m "Say which version this is: ${VERSION}
-
-Set by tools/set-version.sh, which is the only thing that should. The
-workspace, the pacman package and — through Cargo.toml at link time — the
-APK all state ${VERSION}, so a bug report naming a version names one commit.
-
-Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>"
+        git commit -q -m "Release ${VERSION}"
         echo "==> committed: $(git log --oneline -1)"
     fi
 else