Make Actions token permissions explicit

The automatic job token creates the desktop release, so the CD desktop job
asks for contents: write; the images job keeps contents: read and asks for
packages: write so the job token can stand in for the scoped registry PAT.
CI stays read-only. The registry token itself remains a write:package-only
PAT (verified login + pull).

.gitea/workflows/cd.yml

@@ -36,9 +36,14 @@ jobs:
   images:
     name: Build & push images
     runs-on: ubuntu-latest
+    # Registry pushes use the scoped REGISTRY_TOKEN secret; `packages: write`
+    # also lets the automatic job token stand in when that secret is absent.
+    permissions:
+      contents: read
+      packages: write
     env:
       REGISTRY_USER: ${{ secrets.REGISTRY_USER || github.actor }}
-      REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN || secrets.GITHUB_TOKEN }}
+      REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN || secrets.GITEA_TOKEN || secrets.GITHUB_TOKEN }}
       PLATFORMS: ${{ inputs.platforms || 'linux/amd64,linux/arm64' }}
     steps:
       - uses: actions/checkout@v4
@@ -59,6 +64,10 @@ jobs:
   desktop:
     name: Desktop release
     runs-on: ubuntu-latest
+    # Creating the release and uploading its assets uses the automatic job
+    # token, so it needs write access to the repository's releases.
+    permissions:
+      contents: write
     steps:
       - uses: actions/checkout@v4
 
@@ -89,7 +98,7 @@ jobs:
 
       - name: Add the Gitea release
         env:
-          GITEA_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN || secrets.GITHUB_TOKEN }}
         run: |
           set -euo pipefail
           VERSION="$(node -p "require('./desktop/package.json').version")"