feat(server): add Dockerfile.fast and scripts for fast host-compiled builds

- Add Dockerfile.fast which packages a pre-built binary instead of compiling inside the container.
- Add scripts/build-fast.ps1 (PowerShell) and scripts/build-fast.sh (Bash) to automate local cross-compilation (CGO_ENABLED=0 GOOS=linux) and Docker packaging.
- Set executable bit for build-fast.sh.

server/scripts/build-fast.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+# Bash script for fast Docker build using host compilation
+
+set -e
+
+ARCH=${1:-"arm64"}
+TAG=${2:-"x0gp-server:latest"}
+
+# Navigate to the server root directory
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+SERVER_DIR="$(dirname "$SCRIPT_DIR")"
+cd "$SERVER_DIR"
+
+echo "Building Go binary for OS=linux, ARCH=${ARCH}..."
+mkdir -p bin
+BIN_PATH="bin/poc-server-linux-${ARCH}"
+
+# Compile locally
+CGO_ENABLED=0 GOOS=linux GOARCH=${ARCH} go build -ldflags="-s -w" -o "${BIN_PATH}" ./cmd/poc-server
+
+echo "Go binary successfully compiled: ${BIN_PATH}"
+echo "Building Docker image '${TAG}'..."
+
+# Build docker image
+docker build --build-arg BINARY_PATH="${BIN_PATH}" -t "${TAG}" -f Dockerfile.fast .
+
+echo -e "\nDocker image '${TAG}' built successfully!"