fix: use msiextract for tkinter, fix step numbering, graceful Docker fallback

- Replace 7z with msiextract (msitools) to extract tkinter from
  python.org's individual MSI packages (tcltk.msi + lib.msi)
- Fix build step numbering to /9
- Docker job continues on login failure (registry may not be enabled)
- Show makensis output for debugging

.gitea/workflows/release.yml

@@ -63,7 +63,7 @@ jobs:
       - name: Install system dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y --no-install-recommends zip libportaudio2 nsis p7zip-full
+          sudo apt-get install -y --no-install-recommends zip libportaudio2 nsis msitools
 
       - name: Cross-build Windows distribution
         run: |
@@ -188,12 +188,15 @@ jobs:
           echo "server_host=$SERVER_HOST" >> "$GITHUB_OUTPUT"
 
       - name: Login to Gitea Container Registry
+        id: docker-login
+        continue-on-error: true
         run: |
           echo "${{ secrets.GITEA_TOKEN }}" | docker login \
             "${{ steps.meta.outputs.server_host }}" \
             -u "${{ gitea.actor }}" --password-stdin
 
       - name: Build Docker image
+        if: steps.docker-login.outcome == 'success'
         run: |
           TAG="${{ gitea.ref_name }}"
           REGISTRY="${{ steps.meta.outputs.registry }}"
@@ -211,6 +214,7 @@ jobs:
           fi
 
       - name: Push Docker image
+        if: steps.docker-login.outcome == 'success'
         run: |
           TAG="${{ gitea.ref_name }}"
           REGISTRY="${{ steps.meta.outputs.registry }}"