Move COPY commands after package installations for better caching

- Move app source copy in debug stage after apt package installations
- Move app source copy in tests stage after Playwright installation
- Improves Docker layer caching by preventing app changes from invalidating package installation layers

Co-authored-by: dannystaple <426859+dannystaple@users.noreply.github.com>

Author: Copilot

Dockerfile

@@ -9,14 +9,14 @@ RUN npm ci
 
 FROM base AS debug
 
-# Copy app source for development
-COPY . /app/src
-
 RUN apt-get update && apt-get install -y \
     less \
     iputils-ping \
     dnsutils
 
+# Copy app source for development
+COPY . /app/src
+
 FROM dcycle/broken-link-checker:3 AS broken_link_checker
 
 FROM httpd:2.4.64 AS httpd_serve
@@ -47,9 +47,6 @@ COPY . /usr/local/apache2/htdocs/
 
 FROM base AS tests
 
-# Copy app source for testing
-COPY . /app/src
-
 # Install necessary packages for Playwright
 RUN apt-get update && apt-get install -y \
     libnss3 \
@@ -64,6 +61,9 @@ RUN apt-get update && apt-get install -y \
 # Install Playwright browsers
 RUN npx playwright install chromium --with-deps
 
+# Copy app source for testing
+COPY . /app/src
+
 # Set default command to run BDD tests
 CMD ["npm", "run", "test:bdd"]