feat: add binary optimization with strip and upx compression

- Added upx package to Dockerfile.alpine build dependencies
- Added optimize_binary() function to compile-components.sh
- Automatically strips debug symbols from all Zero-OS binaries
- Applies UPX compression with --best --lzma for maximum size reduction
- Optimizes binaries in both initramfs and output directories
- Shows size reduction stats (original → stripped → compressed)
- Graceful fallback if UPX fails, keeping stripped version

This significantly reduces initramfs size by compressing zinit, rfs, and mycelium binaries.

build/Dockerfile.alpine

@@ -27,6 +27,7 @@ RUN apk add --no-cache \
     bc \
     perl \
     python3 \
+    upx \
     # Kernel build dependencies
     linux-lts-dev \
     linux-lts \