ci: optimise docker workflows

Dockerfile.production

@@ -50,8 +50,8 @@ COPY tsconfig.json ./
 # Build production assets
 RUN npm run build
 
-# Stage: Production Runtime
-FROM php:8.5.0RC3-fpm AS production
+# Stage: Runtime Base Image (shared)
+FROM php:8.5.0RC3-fpm AS runtime-base
 
 # Install system dependencies + nginx for production
 RUN apt-get update && apt-get install -y \
@@ -71,7 +71,7 @@ RUN apt-get update && apt-get install -y \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
-# Install PHP extensions
+# Install PHP extensions required at runtime
 RUN docker-php-ext-configure gd \
         --with-freetype \
         --with-jpeg \
@@ -95,13 +95,17 @@ RUN docker-php-ext-install -j$(nproc) \
 RUN pecl install apcu redis-6.3.0RC1 \
     && docker-php-ext-enable apcu redis
 
-# Configure APCu
+# Configure APCu defaults
 RUN echo "apc.enable_cli=1" >> /usr/local/etc/php/conf.d/docker-php-ext-apcu.ini \
     && echo "apc.shm_size=128M" >> /usr/local/etc/php/conf.d/docker-php-ext-apcu.ini
 
-# Install Composer
+# Install Composer into the runtime image for artisan usage
 COPY --from=composer:latest /usr/bin/composer /usr/bin/composer
 
+# Stage: Production Runtime
+ARG RUNTIME_IMAGE=runtime-base
+FROM ${RUNTIME_IMAGE} AS production
+
 # Set working directory
 WORKDIR /var/www/html
 
@@ -128,7 +132,7 @@ RUN mkdir -p storage/logs storage/cache storage/uploads \
     && chown -R www-data:www-data storage \
     && chmod -R 775 storage
 
-# Copy entrypoint script for production
+# Copy entrypoint script for production (overrides runtime base when rebuilt)
 COPY docker/entrypoint.sh /usr/local/bin/entrypoint.sh
 RUN chmod +x /usr/local/bin/entrypoint.sh