feat: initial rpcproxy implementation

High-performance JSON-RPC reverse proxy in Rust with:
- Priority-based failover across multiple upstream RPCs
- Smart caching with method-aware TTLs and request coalescing
- Active health checking via eth_blockNumber
- Bearer token authentication (optional)
- /health, /readiness, /status endpoints
- Docker HEALTHCHECK requiring real block data
- Verbose logging flag for debugging

Author: mahiarirani

.github/workflows/publish_ghcr.yaml

@@ -0,0 +1,53 @@
+name: Publish Docker image to GitHub Packages
+
+on:
+  release:
+    types: [published]
+  push:
+    tags:
+      - "*"
+  workflow_dispatch:
+
+jobs:
+  publish-to-ghcr:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract version from tag and set lowercase repo owner
+        id: meta
+        run: |
+          REF_NAME=${GITHUB_REF#refs/tags/}
+          VERSION=${REF_NAME#v}
+          REPO_OWNER=$(echo $GITHUB_REPOSITORY_OWNER | tr '[:upper:]' '[:lower:]')
+          echo "version=$VERSION" >> $GITHUB_OUTPUT
+          echo "repo_owner=$REPO_OWNER" >> $GITHUB_OUTPUT
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          push: true
+          platforms: linux/amd64,linux/arm64/v8
+          tags: |
+            ghcr.io/${{ steps.meta.outputs.repo_owner }}/rpcproxy:${{ steps.meta.outputs.version }}
+            ghcr.io/${{ steps.meta.outputs.repo_owner }}/rpcproxy:latest
+          labels: |
+            org.opencontainers.image.version=${{ steps.meta.outputs.version }}
+            org.opencontainers.image.source=${{ github.server_url }}/${{ github.repository }}

.gitignore

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+/target
+/.history
+*.log