fix(Dockerfile, Makefile, manifest): Address user/group ID mapping and attempt to resolve ninja errors

Dockerfile

@@ -4,7 +4,11 @@ FROM debian:12-slim
 # Set environment variables for non-interactive install
 ENV DEBIAN_FRONTEND=noninteractive TZ=Etc/UTC
 
-# Install necessary tools: Flatpak, builder, git, etc.
+# Arguments for user and group ID
+ARG UID=1000
+ARG GID=1000
+
+# Install necessary tools: Flatpak, builder, git, ccache, etc.
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
     flatpak \
@@ -14,6 +18,7 @@ RUN apt-get update && \
     unzip \
     ca-certificates \
     elfutils \
+    ccache \
     # Build dependencies for system libraries
     build-essential \
     ninja-build \
@@ -28,15 +33,28 @@ RUN flatpak remote-add --system --if-not-exists flathub https://flathub.org/repo
     flatpak install --system --noninteractive flathub org.freedesktop.Sdk//23.08 && \
     flatpak install --system --noninteractive flathub org.freedesktop.Platform//23.08
 
+# Create a non-root user for the build process
+RUN groupadd -g $GID builder && \
+    useradd -u $UID -g $GID -ms /bin/bash builder && \
+    mkdir -p /home/builder/.cache/ccache && \
+    chown -R builder:builder /home/builder
+
+# Create directories needed for the build and set ownership
+# /sources will be mounted from host, /build is for build artifacts
+RUN mkdir -p /sources /build && \
+    chown -R builder:builder /build
+
+# Set user and home directory
+USER builder
+ENV HOME /home/builder
+ENV CCACHE_DIR /home/builder/.cache/ccache
+ENV PATH /usr/lib/ccache:$PATH
+
 # Set working directory for the build process
 WORKDIR /build
 
-# Create cache-friendly directory structure
-# This creates a clear layer separation for better Docker/Flatpak caching
-RUN mkdir -p /sources /build/cache /build/build-dir /build/repo
-
-# Copy the Flatpak manifest into the build directory
-COPY com.aseprite.Aseprite.yaml .
+# Copy the Flatpak manifest into the build directory (owned by builder due to WORKDIR and USER settings)
+COPY --chown=builder:builder com.aseprite.Aseprite.yaml .
 
 # Default command for interactive use
 CMD ["bash"]