Add mobile-friendly Pyodide REPL (#221)

* Add mobile-friendly Pyodide REPL

A mobile-friendly alternative to pyodide.org/en/stable/console.html
which uses jQuery Terminal and doesn't work well on mobile. Uses a
textarea for input (avoids mobile keyboard issues), with Enter to
run and Shift+Enter for newlines. Supports multiline code, command
history, and micropip package installation.

https://claude.ai/code/session_0127moedQbAB2MR6H3epKAV7

* Rename to pyodide-repl.html, inline input, add multi-line toggle

- Rename pyodide-repo.html -> pyodide-repl.html
- Input area now flows inline after output instead of being anchored
  at the bottom, so it sits where the next >>> line would naturally go
- Add toggle between single-line mode (Enter to run) and multi-line
  mode (Ctrl+Enter to run, Enter inserts newlines) for entering
  function definitions and other multi-line code on mobile
- Add bottom spacer so keyboard doesn't obscure the input
- Include mobile (375x812) and desktop (1024x768) screenshots

https://claude.ai/code/session_0127moedQbAB2MR6H3epKAV7

* Remove screenshots from repo

https://claude.ai/code/session_0127moedQbAB2MR6H3epKAV7

* Add more spacing above the input area

https://claude.ai/code/session_0127moedQbAB2MR6H3epKAV7

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Co-authored-by: Claude <noreply@anthropic.com>

Author: simonw