Fix Dockerfile to build libsignal_ffi dependency

Dockerfile.cloudron

@@ -1,6 +1,6 @@
 FROM cloudron/base:5.0.0@sha256:04fd70dbd8ad6149c19de39e35718e024417c3e01dc9c6637eaf4a41ec4e596c
 
-# Install dependencies
+# Install Rust for building libsignal
 RUN apt-get update && apt-get install -y \
     curl \
     ca-certificates \
@@ -12,9 +12,17 @@ RUN apt-get update && apt-get install -y \
     build-essential \
     libolm-dev \
     gosu \
+    cmake \
+    protobuf-compiler \
+    clang \
+    libclang-dev \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
+# Install Rust
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+ENV PATH="/root/.cargo/bin:$PATH"
+
 # Install Go
 ENV GO_VERSION=1.24.0
 RUN curl -LO https://golang.org/dl/go${GO_VERSION}.linux-amd64.tar.gz \
@@ -28,7 +36,9 @@ WORKDIR /app/code
 
 # Download and build mautrix-signal
 RUN git clone --branch v0.2512.0 https://github.com/mautrix/signal.git . \
-    && go build -o /app/pkg/mautrix-signal ./cmd/mautrix-signal
+    && ./build-rust.sh \
+    && LIBRARY_PATH=/app/code/pkg/libsignalgo/libsignal/target/release ./build-go.sh \
+    && mv mautrix-signal /app/pkg/mautrix-signal
 
 # Copy startup script
 COPY start.sh /app/pkg/