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/Dockerfile.fast

@@ -0,0 +1,19 @@
+# Dockerfile.fast — Fast packaging of a pre-compiled local binary
+FROM alpine:3.19
+
+# Add CA certificates and timezone data
+RUN apk --no-cache add ca-certificates tzdata
+
+WORKDIR /app
+
+# Copy the pre-compiled binary from the host
+ARG BINARY_PATH
+COPY ${BINARY_PATH} /app/poc-server
+
+# Set execution permissions
+RUN chmod +x /app/poc-server
+
+# Expose server ports
+EXPOSE 8080
+
+ENTRYPOINT ["/app/poc-server"]