Added build with Docker

Dockerfile

@@ -0,0 +1,28 @@
+FROM vitasdk/vitasdk:latest
+
+RUN apk add --no-cache \
+    cmake \
+    make \
+    git \
+    ca-certificates
+
+# vdpm is pre-installed at /usr/local/vitasdk/bin/vdpm
+# -f = force install (also works for first-time installs)
+RUN vdpm -f \
+    zlib \
+    libpng \
+    libjpeg-turbo \
+    freetype \
+    openssl \
+    curl \
+    zstd \
+    vita2d
+
+WORKDIR /src
+COPY . .
+
+RUN cmake -B /build -DCMAKE_BUILD_TYPE=Release . && \
+    cmake --build /build --parallel "$(nproc)"
+
+# Mount a host directory to /output to retrieve the VPK
+CMD ["sh", "-c", "cp /build/vitaImmich.vpk /output/vitaImmich.vpk && echo 'Done: /output/vitaImmich.vpk'"]

build.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+IMAGE="vitaimmich-builder"
+OUTPUT_DIR="$(cd "$(dirname "$0")" && pwd)/build"
+
+mkdir -p "$OUTPUT_DIR"
+
+echo "Building Docker image..."
+docker build -t "$IMAGE" "$(dirname "$0")"
+
+echo "Running build..."
+docker run --rm \
+    -v "$OUTPUT_DIR:/output" \
+    "$IMAGE"
+
+echo ""
+echo "VPK ready: $OUTPUT_DIR/vitaImmich.vpk"