Polish store and v2rayA app for release

- Redesign store README as a minimal storefront

- Refine app README and remove technical clutter

- Update Sphera icon with refined vector styling

- Use original v2rayA app icon

- Use raw GitHub URL for v2rayA icon per Umbrel Community Store spec

- Add custom v2rayA image build for UmbrelOS nf_tables iptables

.github/workflows/docker.yml

@@ -0,0 +1,56 @@
+name: Build and publish v2rayA image
+
+on:
+  push:
+    branches: [master]
+    paths:
+      - 'sphera-v2raya/Dockerfile'
+      - '.github/workflows/docker.yml'
+  workflow_dispatch:
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository_owner }}/sphera-v2raya
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=raw,value=v2.4.9-2
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: ./sphera-v2raya
+          file: ./sphera-v2raya/Dockerfile
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max