Add OpenWrt ipk packaging + split client/server binaries

OpenWrt package (deploy/openwrt/):
- build-ipk.sh: creates .ipk from pre-built binary (no SDK needed)
- Makefile: for OpenWrt SDK integration
- ProCD init script with UCI config
- Supports all architectures (x86_64, aarch64, mipsel, mips)

Split binaries for embedded (src/bin/):
- btest-client: client-only, no server/syslog/csv
- btest-server: server-only, no client
- release-small profile: opt-level=z + panic=abort

Sizes (compressed .tar.gz):
  Full btest:    ~1 MB
  btest-client:  ~500 KB (release-small)
  btest-server:  ~550 KB (release-small)

Install on OpenWrt:
  opkg install btest-rs_0.6.0-1_x86_64.ipk

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

deploy/openwrt/build-ipk.sh

@@ -0,0 +1,117 @@
+#!/usr/bin/env bash
+# Build an OpenWrt .ipk package from a pre-built static binary.
+# No OpenWrt SDK needed — just packages the binary with metadata.
+#
+# Usage:
+#   ./deploy/openwrt/build-ipk.sh <arch> [binary-path]
+#
+# Examples:
+#   ./deploy/openwrt/build-ipk.sh x86_64 dist/btest           # from cross-compiled binary
+#   ./deploy/openwrt/build-ipk.sh aarch64 dist/btest           # for RPi/ARM64 routers
+#   ./deploy/openwrt/build-ipk.sh mipsel target/release/btest  # for MIPS little-endian
+#
+# Supported architectures: x86_64, aarch64, arm_cortex-a7, mipsel_24kc, mips_24kc
+set -euo pipefail
+
+cd "$(dirname "$0")/../.."
+
+ARCH="${1:?Usage: $0 <arch> [binary-path]}"
+BINARY="${2:-dist/btest}"
+VERSION="0.6.0"
+PKG_NAME="btest-rs"
+OUTPUT_DIR="dist"
+
+if [ ! -f "$BINARY" ]; then
+    echo "Error: binary not found at $BINARY"
+    echo "Build it first: cargo build --release --target <target>"
+    exit 1
+fi
+
+mkdir -p "$OUTPUT_DIR"
+WORKDIR=$(mktemp -d)
+trap "rm -rf $WORKDIR" EXIT
+
+echo "=== Building ${PKG_NAME}_${VERSION}_${ARCH}.ipk ==="
+
+# Create package structure
+mkdir -p "$WORKDIR/data/usr/bin"
+mkdir -p "$WORKDIR/data/etc/init.d"
+mkdir -p "$WORKDIR/data/etc/config"
+mkdir -p "$WORKDIR/control"
+
+# Install files
+cp "$BINARY" "$WORKDIR/data/usr/bin/btest"
+chmod 755 "$WORKDIR/data/usr/bin/btest"
+cp deploy/openwrt/files/btest.init "$WORKDIR/data/etc/init.d/btest"
+chmod 755 "$WORKDIR/data/etc/init.d/btest"
+cp deploy/openwrt/files/btest.config "$WORKDIR/data/etc/config/btest"
+
+# Calculate installed size
+INSTALLED_SIZE=$(du -sk "$WORKDIR/data" | awk '{print $1}')
+
+# Control file
+cat > "$WORKDIR/control/control" << EOF
+Package: ${PKG_NAME}
+Version: ${VERSION}-1
+Depends: libc
+Source: https://github.com/manawenuz/btest-rs
+License: MIT AND Apache-2.0
+Section: net
+SourceName: ${PKG_NAME}
+Maintainer: Siavash Sameni <manwe@manko.yoga>
+Architecture: ${ARCH}
+Installed-Size: ${INSTALLED_SIZE}
+Description: MikroTik Bandwidth Test server and client
+ A Rust reimplementation of the MikroTik btest protocol.
+ Supports TCP/UDP, EC-SRP5 and MD5 auth, IPv4/IPv6.
+EOF
+
+# Post-install script
+cat > "$WORKDIR/control/postinst" << 'EOF'
+#!/bin/sh
+[ "${IPKG_NO_SCRIPT}" = "1" ] && exit 0
+/etc/init.d/btest enable 2>/dev/null || true
+exit 0
+EOF
+chmod 755 "$WORKDIR/control/postinst"
+
+# Pre-remove script
+cat > "$WORKDIR/control/prerm" << 'EOF'
+#!/bin/sh
+/etc/init.d/btest stop 2>/dev/null || true
+/etc/init.d/btest disable 2>/dev/null || true
+exit 0
+EOF
+chmod 755 "$WORKDIR/control/prerm"
+
+# Conffiles
+cat > "$WORKDIR/control/conffiles" << EOF
+/etc/config/btest
+EOF
+
+# Build the .ipk (it's just a tar.gz of tar.gz's)
+cd "$WORKDIR"
+
+# Create data.tar.gz
+(cd data && tar czf ../data.tar.gz .)
+
+# Create control.tar.gz
+(cd control && tar czf ../control.tar.gz .)
+
+# Create debian-binary
+echo "2.0" > debian-binary
+
+# Package it all
+tar czf "${PKG_NAME}_${VERSION}-1_${ARCH}.ipk" debian-binary control.tar.gz data.tar.gz
+
+cd -
+cp "$WORKDIR/${PKG_NAME}_${VERSION}-1_${ARCH}.ipk" "$OUTPUT_DIR/"
+
+echo ""
+echo "Package: $OUTPUT_DIR/${PKG_NAME}_${VERSION}-1_${ARCH}.ipk"
+ls -lh "$OUTPUT_DIR/${PKG_NAME}_${VERSION}-1_${ARCH}.ipk"
+echo ""
+echo "Install on OpenWrt:"
+echo "  scp $OUTPUT_DIR/${PKG_NAME}_${VERSION}-1_${ARCH}.ipk root@router:/tmp/"
+echo "  ssh root@router 'opkg install /tmp/${PKG_NAME}_${VERSION}-1_${ARCH}.ipk'"
+echo "  ssh root@router '/etc/init.d/btest enable && /etc/init.d/btest start'"