chore(web): remove 404 page image to reduce bundle size

[tyler-dane]

Summary

• Remove the 516KB decorative image from the 404 page to reduce bundle size
• The pirate-themed text and emoji (🏴‍☠️ "Shiver me timbers!") provide sufficient visual feedback

Context

This is part of an effort to minimize the web bundle size. Analysis of build/web revealed:

Asset	Size	Notes
chunk-*.js.map	12MB	Source map (not downloaded by users)
chunk-*.js	3.5MB	Main bundle (~960KB gzipped)
notFound-*.png	516KB	Decorative 404 image

The 404 page image was the third largest asset in the build, yet it's only seen when users navigate to an invalid route—a rare occurrence by design.

Bundle Impact

• 516KB removed from build output
• ~100KB less network transfer (estimated gzipped savings)
• Faster build times (one fewer large asset to process)

Related

See #1686 for a larger bundle optimization opportunity: replacing react-cmdk with a native command palette to eliminate the transitive @heroicons/react dependency (975 bundled icon files).

Test plan

• Navigate to an invalid route (e.g., /invalid-path)
• Verify 404 page displays correctly with pirate text and button
• Verify "Go back to your booty" button navigates home

🤖 Generated with Claude Code

[tyler-dane]