Move frontend workflow to root .gitea/workflows

Gitea Actions only detects workflows at repo root, not subdirectories.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/.gitea/workflows/build.yaml

@@ -1,49 +0,0 @@
-name: Build and Push Frontend Docker Image
-
-on:
-  push:
-    branches:
-      - main
-    paths:
-      - 'frontend/**'
-      - '.gitea/workflows/build-frontend.yaml'
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    timeout-minutes: 30
-    container:
-      image: catthehacker/ubuntu:act-latest
-
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@v4
-
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
-
-      - name: Login to Gitea Registry
-        uses: docker/login-action@v3
-        with:
-          registry: gitea.voyager.sh
-          username: ${{ secrets.REGISTRY_USERNAME }}
-          password: ${{ secrets.REGISTRY_TOKEN }}
-
-      - name: Extract metadata
-        id: meta
-        uses: docker/metadata-action@v5
-        with:
-          images: gitea.voyager.sh/nick/comfyui-frontend
-          tags: |
-            type=sha,prefix=
-            type=raw,value=latest
-
-      - name: Build and push
-        uses: docker/build-push-action@v5
-        with:
-          context: ./frontend
-          push: true
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
-          cache-from: type=gha
-          cache-to: type=gha,mode=max