feat: ✨ add environment variable support for proxy authentication and geo-blocking

- Introduced `.env.example` for environment variable configuration.
- Updated `docker-compose.yml` to utilize environment variables for proxy settings.
- Implemented proxy authentication with Basic Auth and geo-blocking based on country codes.
- Added `GEO_FILTER.md` for documentation on geo-filtering configuration.
- Enhanced logging to indicate authentication status and blocked countries during proxy server startup.

.github/workflows/docker-image.yml

@@ -0,0 +1,72 @@
+name: Docker Image CI
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - 'v*'
+  workflow_dispatch:
+
+env:
+  REGISTRY_DOCKERHUB: docker.io
+  REGISTRY_GHCR: ghcr.io
+  IMAGE_NAME: isboyjc/goproxy
+
+jobs:
+  build-and-push:
+    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: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            ${{ env.REGISTRY_DOCKERHUB }}/${{ env.IMAGE_NAME }}
+            ${{ env.REGISTRY_GHCR }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=ref,event=branch
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+            type=raw,value=latest,enable={{is_default_branch}}
+      
+      - name: Login to Docker Hub
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY_DOCKERHUB }}
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      
+      - name: Login to GitHub Container Registry
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY_GHCR }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max