Add Keybr-inspired typing trainer (typing-trainer)

[anyz6x]

Why

Provide a lightweight, self-contained typing trainer inspired by keybr.com so contributors and users can run a small demo locally, practice typing, and prototype UI/UX without pulling the full site.

What this change does

• Adds a new folder typing-trainer/ containing a minimal standalone app: index.html, style.css, app.js, and README.md.
• Implements real-time WPM and accuracy calculation, lesson selection/progression, an on-screen keyboard with pressed-key highlights, and a polished dark UI inspired by keybr.com.
• No external dependencies required; the app runs by opening typing-trainer/index.html in a browser or serving the folder with a static server.

Important notes and testing

• This is a small, standalone scaffold intended for local testing and iteration. To run locally: open typing-trainer/index.html or run npx http-server typing-trainer -p 8080 from the repo root.
• The branch was pushed to the contributor fork to create the PR. If reviewers want the trainer integrated into the main site, that can be done in a follow-up change.

Non-obvious decisions / trade-offs

• Kept the implementation intentionally minimal and dependency-free so it is easy to review and run. Future PRs can add persistence, more lessons, analytics, and integration with the existing site structure.

Follow-ups

• Add more lessons and i18n content
• Integrate the trainer into the main site UI or package as a reusable component
• Add unit/e2e tests and accessibility improvements

N/A

[semanticdiff-com]

Review changes with  

Changed Files

File	Status
typing-trainer/README.md	Unsupported file format
typing-trainer/app.js	0% smaller
typing-trainer/index.html	0% smaller
typing-trainer/style.css	0% smaller