feat: add sm64coopdx headless dedicated server

Multi-stage Docker build compiles sm64coopdx from source with HEADLESS=1.
Includes patches for GCC 11 float.h and upstream platform.c fallback bug.
Server runs on UDP 7777, supports 16 players, comes with bundled mods.

Also hardcodes OpenFusion SHARD_IP (was using PUBLIC_HOST variable).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

servers/sm64coopdx/.dockerignore

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+*.md
+.git

servers/sm64coopdx/.gitignore

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+# SM64 ROM — copyrighted, not distributable
+*.z64
+*.n64
+*.v64

servers/sm64coopdx/Dockerfile

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+# sm64coopdx headless dedicated server
+# Requires baserom.us.z64 (SM64 US ROM) in build context
+
+# --- Build stage ---
+FROM ubuntu:jammy AS build
+
+RUN apt-get update && apt-get install -y \
+    binutils-mips-linux-gnu \
+    bsdmainutils \
+    build-essential \
+    libcapstone-dev \
+    pkgconf \
+    python3 \
+    libz-dev \
+    libcurl4-openssl-dev \
+    git \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /sm64
+
+RUN git clone --depth 1 https://github.com/coop-deluxe/sm64coopdx.git .
+
+COPY baserom.us.z64 .
+
+# Patch: add missing float.h include (GCC 11 strictness)
+RUN sed -i '1i #include <float.h>' src/engine/math_util.c
+
+# Patch: fix platform.c fallback — upstream renamed functions but forgot the #else branch
+RUN sed -i 's/const char \*sys_exe_path(void) {/const char *sys_exe_path_dir(void) {\n    return ".";\n}\n\nconst char *sys_resource_path(void) {\n    return ".";\n}\n\nconst char *sys_exe_path(void) {/' src/pc/platform.c
+
+RUN make HEADLESS=1 DISCORD_SDK=0 COOPNET=0 -j$(nproc)
+
+# --- Runtime stage ---
+FROM ubuntu:jammy
+
+RUN apt-get update && apt-get install -y \
+    libcurl4 \
+    libz1 \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN useradd -m -s /bin/bash sm64
+
+WORKDIR /server
+
+COPY --from=build /sm64/build/us_pc/ .
+COPY --from=build /sm64/baserom.us.z64 .
+
+RUN mkdir -p /server/mods /server/save && chown -R sm64:sm64 /server
+
+USER sm64
+
+EXPOSE 7777/udp
+
+ENV SM64_PORT=7777
+ENV SM64_PLAYERS=16
+
+ENTRYPOINT ["sh", "-c", "./sm64coopdx --server ${SM64_PORT} --headless --playercount ${SM64_PLAYERS} --skip-intro"]