fix: Wine locale crash and rename secrets off the GITEA_ prefix

C.UTF-8 for the win/AppImage build step: Wine's makensis was aborting
with ERR_ELECTRON_BUILDER_CANNOT_EXECUTE / "main argv conversion
failed!" under the runner's default C/POSIX locale.

Gitea rejects secret names starting with GITEA, so the registry/API
credentials are now BUILD_USER/BUILD_TOKEN.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -14,8 +14,10 @@ name: Release
 #
 # Requires two Actions secrets on this repo (Settings > Actions > Secrets), a
 # token with package read/write *and* repository write (write:repository) scope:
-#   GITEA_USER  - registry/API username
-#   GITEA_TOKEN - registry/API token
+#   BUILD_USER  - registry/API username
+#   BUILD_TOKEN - registry/API token
+# (named BUILD_* rather than GITEA_* because Gitea rejects secrets whose name
+# starts with GITEA)
 
 on:
   push:
@@ -81,14 +83,20 @@ jobs:
         shell: pwsh
         env:
           TAG: ${{ steps.vars.outputs.tag }}
+          # Wine's argv conversion aborts with ERR_ELECTRON_BUILDER_CANNOT_EXECUTE
+          # / "main argv conversion failed!" under the C/POSIX locale that a
+          # minimal Debian box defaults to. C.UTF-8 is a glibc built-in, no
+          # locale-gen needed.
+          LANG: C.UTF-8
+          LC_ALL: C.UTF-8
         run: ./scripts/build-release.ps1 -Targets win,linux-appimage -Tag $env:TAG
 
       - name: Log in to git.azuze.fr
         uses: docker/login-action@v3
         with:
           registry: git.azuze.fr
-          username: ${{ secrets.GITEA_USER }}
-          password: ${{ secrets.GITEA_TOKEN }}
+          username: ${{ secrets.BUILD_USER }}
+          password: ${{ secrets.BUILD_TOKEN }}
 
       - uses: docker/setup-buildx-action@v3
 
@@ -104,7 +112,7 @@ jobs:
       - name: Publish Gitea release
         env:
           TAG: ${{ steps.vars.outputs.tag }}
-          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+          GITEA_TOKEN: ${{ secrets.BUILD_TOKEN }}
           SERVER_URL: ${{ github.server_url }}
           REPO_PATH: ${{ github.repository }}
         run: |