ci(desktop): a rebuild by hand takes only a Codeman release tag on master

A dispatch with -f tag=<any tag> built that tag, and sign then ran the tag's
sign-macos.sh with the Developer ID key unlocked and the notary login in its
environment. Nothing checked the tag: xterm-zerolag-input@0.1.7 would have put
Codeman.dmg on that package's release, and a tag on a commit that never
reached master would have run unreviewed scripts with the secrets.

build and sign now each check their own checkout before anything else runs:
the tag must read codeman@x.y.z (or aicodeman@x.y.z, which a failed rename
leaves) and GitHub's compare of master with the checked-out commit must say
behind or identical. The check is inline, since a script from the checkout
would be the tag's own code. Release's own call (a push, not a dispatch) and
the branch dry run are unchanged.

The header says why a master-only Environment would not close this path, and
release.yml's macos-app job now says that any permission a called job asks
for must be granted there too, or Release fails at startup.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/release.yml

@@ -145,8 +145,12 @@ jobs:
     name: macOS app
     needs: release
     if: needs.release.outputs.codeman_version != ''
+    # The ceiling for the called jobs; only its attach job asks for write. A job in
+    # desktop-dmg.yml that asks for a permission not granted here (id-token or
+    # attestations for a provenance attestation, say) makes GitHub refuse this
+    # whole Release run at startup, npm publish included: widen both together.
     permissions:
-      contents: write # the ceiling for the called jobs; only its attach job asks for write
+      contents: write
     uses: ./.github/workflows/desktop-dmg.yml
     with:
       tag: codeman@${{ needs.release.outputs.codeman_version }}