release.yaml: authenticate the version-resolution API calls

The /releases/latest and /releases/tags/X reads were unauthenticated. On
private repos Forgejo returns 404 to unauth'd callers, so the workflow
silently fell back to v0.0.0 as the "previous version" and let a
BUMP_PATCH on top of v1.x.y produce v0.0.1. The duplicate-tag guard had
the same blind spot — it could not detect existing releases at all.

Both reads now send the Authorization header and treat any non-200 /
non-404 response as a hard failure instead of swallowing it.

.forgejo/workflows/release.yaml

@@ -41,19 +41,33 @@ jobs:
     steps:
       - name: Resolve version
         id: version
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
+          set -euo pipefail
           VERSION_TYPE="${{ inputs.version_type }}"
           SPECIFIC_VERSION="${{ inputs.specific_version }}"
 
           FORGE_URL="${{ github.server_url }}/api/v1/repos/${{ github.repository }}"
           echo "Fetching latest release..."
-          LATEST=$(curl -s "${FORGE_URL}/releases/latest" | jq -r '.tag_name // empty' || true)
+          # Private repos return 404 to unauthenticated callers, so the auth
+          # header is required even though "latest release" reads like public
+          # info. Without it the curl 404s, falls back to v0.0.0, and a
+          # BUMP_PATCH on top of v1.x.y silently produces v0.0.1.
+          LATEST_STATUS=$(curl -s -o /tmp/latest.json -w "%{http_code}" \
+            -H "Authorization: token $GITHUB_TOKEN" \
+            "${FORGE_URL}/releases/latest")
 
-          if [ -z "$LATEST" ]; then
+          if [ "$LATEST_STATUS" = "200" ]; then
+            LATEST=$(jq -r '.tag_name' < /tmp/latest.json)
+            echo "Latest release: $LATEST"
+          elif [ "$LATEST_STATUS" = "404" ]; then
             LATEST="v0.0.0"
             echo "No previous releases found, using base version: $LATEST"
           else
-            echo "Latest release: $LATEST"
+            echo "Error: unexpected HTTP $LATEST_STATUS fetching latest release"
+            cat /tmp/latest.json
+            exit 1
           fi
 
           CURRENT="${LATEST#v}"
@@ -92,9 +106,18 @@ jobs:
               ;;
           esac
 
-          if curl -sf "${FORGE_URL}/releases/tags/$VERSION" > /dev/null 2>&1; then
+          # Same auth requirement: on a private repo, an unauthenticated
+          # curl always 404s here, which would silently disable the
+          # "release already exists" guard.
+          EXISTS_STATUS=$(curl -s -o /dev/null -w "%{http_code}" \
+            -H "Authorization: token $GITHUB_TOKEN" \
+            "${FORGE_URL}/releases/tags/$VERSION")
+          if [ "$EXISTS_STATUS" = "200" ]; then
             echo "Error: Release $VERSION already exists"
             exit 1
+          elif [ "$EXISTS_STATUS" != "404" ]; then
+            echo "Error: unexpected HTTP $EXISTS_STATUS checking for existing release"
+            exit 1
           fi
 
           echo "version=$VERSION" >> "$GITHUB_OUTPUT"