Add libproxyprotocol to the Debian, Rocky, and Alpine build environments

Upstream ships only a Makefile with no install target, so each image
compiles src/proxy_protocol.c with -fPIC, archives it into
libproxyprotocol.a, and installs the header manually, matching this
project's static-PIC-library convention.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016Xj6cCTEVsr5PM43uTsbq8

debian13/Dockerfile

@@ -563,4 +563,16 @@ RUN git clone --branch=5.3.1 --depth=1 https://github.com/jemalloc/jemalloc.git
     && cd .. \
     && rm -rf src
 
+RUN curl --fail --location --output libproxyprotocol.tar.gz \
+        https://gh-proxy.com/https://github.com/kosmas-valianos/libproxyprotocol/archive/v1.3.3.tar.gz \
+    && echo "4f1cbd714e5b52a91a9a43228d55c8165b578b738f743d057ae321b69b8437f7  libproxyprotocol.tar.gz" \
+        | sha256sum --check - \
+    && mkdir src \
+    && tar --extract --gzip --file=libproxyprotocol.tar.gz --directory=src --strip-components=1 \
+    && rm libproxyprotocol.tar.gz \
+    && gcc -fPIC -c -o src/src/proxy_protocol.o src/src/proxy_protocol.c \
+    && ar rcs /usr/local/lib/libproxyprotocol.a src/src/proxy_protocol.o \
+    && cp src/src/proxy_protocol.h /usr/local/include/ \
+    && rm -rf src
+
 CMD ["/bin/bash"]