Add screenshots to all app READMEs

[corvid-agent]

Moved from CorvidLabs/corvid-agent#169

READMEs were updated with proper descriptions but lack visual previews. For each repo:

• Take desktop screenshot of the main view
• Take mobile screenshot (375px width)
• Add to README with image markdown
• Consider animated GIFs for interactive features (games, maps, charts)

Repos: weather-dashboard, space-dashboard, bw-cinema, pd-gallery, pd-audiobooks, pd-music, poetry-atlas, quake-tracker, retro-arcade, pixel-forge, agent-dashboard, agent-profile, algo-explorer, corvid-agent-chat