ci: use sparse checkout for release notes in release workflow

Only fetch RELEASE_NOTES.md instead of full repo checkout, and
simplify the file detection to a direct path check.

.gitea/workflows/release.yml

@@ -12,8 +12,11 @@ jobs:
     outputs:
       release_id: ${{ steps.create.outputs.release_id }}
     steps:
-      - name: Checkout
+      - name: Fetch RELEASE_NOTES.md only
         uses: actions/checkout@v4
+        with:
+          sparse-checkout: RELEASE_NOTES.md
+          sparse-checkout-cone-mode: false
 
       - name: Create Gitea release
         id: create
@@ -33,11 +36,9 @@ jobs:
           REPO=$(echo "${{ gitea.repository }}" | tr '[:upper:]' '[:lower:]')
           DOCKER_IMAGE="${SERVER_HOST}/${REPO}"
 
-          # Scan for RELEASE_NOTES.md (check repo root first, then recursively)
-          NOTES_FILE=$(find . -maxdepth 3 -name "RELEASE_NOTES.md" -type f | head -1)
-          if [ -n "$NOTES_FILE" ]; then
-            export RELEASE_NOTES=$(cat "$NOTES_FILE")
-            echo "Found release notes: $NOTES_FILE"
+          if [ -f RELEASE_NOTES.md ]; then
+            export RELEASE_NOTES=$(cat RELEASE_NOTES.md)
+            echo "Found RELEASE_NOTES.md"
           else
             export RELEASE_NOTES=""
             echo "No RELEASE_NOTES.md found"