feat: add repository-scoped cache token for action binaries

Add a new optional cache-token input to both published actions.

- Default cache key token is now action_repository + release_tag.
- Cache key uses this token plus runner architecture.
- prepare-release workflow passes github.sha as a fixed token.

This prevents cross-repository cache collisions when consumers pull
vociferate binaries produced by this repository.

prepare/action.yml

@@ -48,6 +48,12 @@ inputs:
       custom version-file.
     required: false
     default: 'changelog.md release-version'
+  cache-token:
+    description: >
+      Optional fixed cache token used for the downloaded binary cache key.
+      Defaults to action repository plus release tag.
+    required: false
+    default: ''
 
 outputs:
   version:
@@ -63,6 +69,8 @@ runs:
       shell: bash
       env:
         ACTION_REF: ${{ github.action_ref }}
+        ACTION_REPOSITORY: ${{ github.action_repository }}
+        CACHE_TOKEN_INPUT: ${{ inputs.cache-token }}
         SERVER_URL: ${{ github.server_url }}
         API_URL: ${{ github.api_url }}
         TOKEN: ${{ inputs.token != '' && inputs.token || github.token }}
@@ -88,10 +96,18 @@ runs:
           binary_path="${cache_dir}/vociferate"
           asset_url="${SERVER_URL}/aether/vociferate/releases/download/${release_tag}/${asset_name}"
 
+          provided_cache_token="$(printf '%s' "${CACHE_TOKEN_INPUT:-}" | sed 's/^[[:space:]]\+//; s/[[:space:]]\+$//')"
+          if [[ -n "$provided_cache_token" ]]; then
+            cache_token="$provided_cache_token"
+          else
+            cache_token="${ACTION_REPOSITORY:-aether/vociferate}-${release_tag}"
+          fi
+
           mkdir -p "$cache_dir"
 
           echo "use_binary=true"          >> "$GITHUB_OUTPUT"
           echo "release_tag=$release_tag" >> "$GITHUB_OUTPUT"
+          echo "cache_token=$cache_token" >> "$GITHUB_OUTPUT"
           echo "asset_name=$asset_name"   >> "$GITHUB_OUTPUT"
           echo "asset_url=$asset_url"     >> "$GITHUB_OUTPUT"
           echo "cache_dir=$cache_dir"     >> "$GITHUB_OUTPUT"
@@ -114,7 +130,7 @@ runs:
       uses: actions/cache@v4
       with:
         path: ${{ steps.resolve-binary.outputs.cache_dir }}
-        key: vociferate-${{ steps.resolve-binary.outputs.release_tag }}-linux-${{ runner.arch }}
+        key: vociferate-${{ steps.resolve-binary.outputs.cache_token }}-linux-${{ runner.arch }}
 
     - name: Download vociferate binary
       if: steps.resolve-binary.outputs.use_binary == 'true' && steps.cache-vociferate.outputs.cache-hit != 'true'