CLI Components

# CLI Components - Ralph Wiggum Prompt

## Your Mission

Implement 4 React components that pass all unit and E2E tests. The components must follow CLI/terminal aesthetic styling.

## Success Criteria

Run these commands:

```bash
npm test           # All unit tests must pass
npm run test:e2e   # All E2E tests must pass (runs in real browser)
npm run typecheck  # No TypeScript errors
npm run build      # Must build successfully
```

When ALL FOUR pass, output: **RALPH_WIGGUM_COMPLETE**

**IMPORTANT:** Unit tests run in jsdom (simulated browser), E2E tests run in real Chrome. Code that passes unit tests may fail in real browsers. If E2E fails with errors like "Illegal invocation", your code has browser compatibility issues.

## Components to Implement

1. **TypingEffect** - Animated terminal-style typing with blinking cursor
2. **ProgressBar** - Accessible progress indicator with color variants
3. **Collapsible** - Expandable content section with keyboard nav
4. **CopyButton** - Copy to clipboard with success/error feedback

## Common Pitfalls

1. Forgetting cleanup: Always clear intervals/timeouts in useEffect cleanup
2. Missing test IDs: Tests rely on exact data-testid values
3. Timer function context (CRITICAL): In browsers, setInterval/setTimeout must be called directly, NOT stored in variables:

```javascript
// BAD - fails in browser with "Illegal invocation"
const mySetInterval = setInterval;
mySetInterval(() => {}, 100);

// GOOD - works everywhere
setInterval(() => {}, 100);
```