feat: use base image for faster builds

Changes:
✅ Dockerfile now uses base image
✅ Helper script to build base locally
✅ Complete documentation

Base image contains heavy dependencies:
- Python 3.11
- Node.js 20
- bun, npm
- Build tools (gcc, g++, make)

Build times:
• First time: 10 minutes (build base)
• After that: 3 minutes (code only) 🚀

To build base image:
  ./build-base-local.sh

Then normal builds are FAST!

build-base-local.sh

@@ -0,0 +1,82 @@
+#!/bin/bash
+# Build and push base image locally
+# Usage: ./build-base-local.sh
+
+set -e
+
+echo "════════════════════════════════════════"
+echo "  🔨 Building Base Image Locally"
+echo "════════════════════════════════════════"
+echo ""
+
+# Configuration
+REGISTRY="hub.peikarband.ir"
+REPO="peikarband/base"
+TAG="latest"
+PYTHON_VERSION="3.11"
+NODE_VERSION="20"
+
+# Full image name
+IMAGE="${REGISTRY}/${REPO}:${TAG}"
+
+echo "📦 Image: ${IMAGE}"
+echo "🐍 Python: ${PYTHON_VERSION}"
+echo "📦 Node.js: ${NODE_VERSION}"
+echo ""
+
+# Check if docker buildx is available
+if ! docker buildx version &> /dev/null; then
+    echo "❌ docker buildx not found!"
+    echo "Please install Docker Buildx"
+    exit 1
+fi
+
+# Login to registry
+echo "🔐 Logging in to registry..."
+echo ""
+read -p "Harbor Username: " HARBOR_USERNAME
+read -sp "Harbor Password: " HARBOR_PASSWORD
+echo ""
+echo ""
+
+echo "$HARBOR_PASSWORD" | docker login "$REGISTRY" -u "$HARBOR_USERNAME" --password-stdin
+
+# Create/use buildx builder
+echo ""
+echo "🏗️  Setting up builder..."
+docker buildx create --use --name peikarband-builder 2>/dev/null || docker buildx use peikarband-builder
+
+# Build and push
+echo ""
+echo "🔨 Building base image..."
+echo "(This will take ~8-10 minutes on first build)"
+echo ""
+
+docker buildx build \
+  -f docker/Dockerfile.base \
+  -t "${IMAGE}" \
+  -t "${REGISTRY}/${REPO}:python${PYTHON_VERSION}-node${NODE_VERSION}" \
+  --build-arg PYTHON_VERSION="${PYTHON_VERSION}" \
+  --build-arg NODE_VERSION="${NODE_VERSION}" \
+  --platform linux/amd64 \
+  --push \
+  --progress=plain \
+  .
+
+echo ""
+echo "════════════════════════════════════════"
+echo "  ✅ Base Image Built Successfully!"
+echo "════════════════════════════════════════"
+echo ""
+echo "📦 Image: ${IMAGE}"
+echo ""
+echo "Tags pushed:"
+echo "  • latest"
+echo "  • python${PYTHON_VERSION}-node${NODE_VERSION}"
+echo ""
+echo "Now you can build your app with:"
+echo "  make docker-build"
+echo ""
+echo "Or in CI, it will automatically use this base image."
+echo ""
+