Add batch screenshot documentation with configuration guide

[Copilot]

Adds comprehensive documentation for the pyrobird screenshot command, which previously lacked usage examples and configuration details.

Documentation Added

• Installation: Playwright setup with chromium binaries
• Command options table: All 6 CLI flags with defaults and descriptions
• Configuration details: Viewport (1920x1080), full-page mode, timeouts, headless Chromium
• Examples:
  • Custom output paths with auto-numbering
  • Specific event URLs
  • Batch processing script template for multiple events
  • Programmatic Python usage
• Troubleshooting: Playwright installation, server startup, incomplete renders, permissions

Example Batch Script

for event in {0..9}; do
    pyrobird screenshot \
        --work-path="$DATA_PATH" \
        --url "http://localhost:5454/#/event?file=local://$DATA_FILE&event=$event" \
        --output-path "event_${event}.png"
done

Screenshots auto-save to screenshots/ directory with numbering to prevent overwrites (event_001.png, event_001_001.png, etc.).

Files Modified

• doc/pyrobird.md: Added batch screenshot section (+217 lines)
• pyrobird/README.md: Added batch screenshot section (+217 lines)

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add documentation of how to make batch screenshots</issue_title>
<issue_description>And control their config
</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add documentation of how to make batch screenshots #69

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