Remove incompatible GitHub Actions cache from workflow

Remove cache-from and cache-to settings using type=gha, which are
incompatible with Gitea runners. The build completes successfully
but fails when trying to export to the non-existent GHA cache service.

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

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

.github/workflows/main.yml

@@ -27,7 +27,6 @@ jobs:
       packages: write
     env:
       TARGET_PLATFORM: linux-arm64
-      BUILD_CACHE_SCOPE: ws14-docker-linux-server-arm64
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
@@ -65,10 +64,6 @@ jobs:
         with:
           context: .
           platforms: linux/arm64
-          cache-from: |
-            type=gha,scope=${{ env.BUILD_CACHE_SCOPE }}
-          cache-to: |
-            type=gha,scope=${{ env.BUILD_CACHE_SCOPE }},mode=max,compression=zstd
           push: true
           tags: |
             ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:arm64
@@ -88,7 +83,6 @@ jobs:
       packages: write
     env:
       TARGET_PLATFORM: linux-x64
-      BUILD_CACHE_SCOPE: ws14-docker-linux-server-amd64
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
@@ -126,10 +120,6 @@ jobs:
         with:
           context: .
           platforms: linux/amd64
-          cache-from: |
-            type=gha,scope=${{ env.BUILD_CACHE_SCOPE }}
-          cache-to: |
-            type=gha,scope=${{ env.BUILD_CACHE_SCOPE }},mode=max,compression=zstd
           push: true
           tags: |
             ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest