feat: Add Focus Tools (ADHD-friendly productivity features)

- Add Focus Tools dashboard with collapsible help section
- Implement Quick Wins page for tasks under 15 minutes
- Add Single Task Focus mode to reduce overwhelm
- Create Body Doubling page for virtual co-working
- Add visual timer, break reminders, and energy tracking
- Implement hyperfocus protection alerts
- Add ADHD settings panel with customizable options
- Include full English and German translations
- Fix larger touch targets CSS to not break button layouts
- Add Playwright tests for Focus Tools features

Dockerfile

@@ -5,7 +5,7 @@ WORKDIR /app
 # Dependencies stage
 FROM base AS dependencies
 COPY package.json package-lock.json ./
-RUN npm ci --only=production && \
+RUN npm ci --omit=dev && \
   cp -R node_modules /tmp/prod_node_modules && \
   npm ci