add ccache and cache mounts

Dockerfile

@@ -5,6 +5,7 @@ ARG DEBIAN_FRONTEND=noninteractive
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
   build-essential \
+  ccache \
   cmake \
   ninja-build \
   file \
@@ -18,15 +19,22 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   qt6-tools-dev \
   qt6-tools-dev-tools
 
+ENV CCACHE_DIR=/root/.ccache
+ENV CCACHE_MAXSIZE=550M
 WORKDIR /src
 COPY . .
-RUN cmake -S . -B build \
-  -G Ninja \
-  -DWITH_SERVER=1 \
-  -DWITH_CLIENT=0 \
-  -DWITH_ORACLE=0 \
-    && cmake --build build \
-    && cmake --install build
+RUN --mount=type=cache,target=/root/.ccache \
+  cmake -S . -B build \
+    -G Ninja \
+    -DCMAKE_C_COMPILER_LAUNCHER=ccache \
+    -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \
+    -DWITH_SERVER=1 \
+    -DWITH_CLIENT=0 \
+    -DWITH_ORACLE=0 \
+      && cmake --build build \
+      && cmake --install build
+
+RUN ccache --show-stats
 
 
 # -------- Runtime Stage (clean) --------