Add cryptocurrency price command via CoinGecko API

New features:
- !crypto <SYMBOL> command to query cryptocurrency prices
- CoinGeckoAPI integration (free, no API key required)
- Support for 20+ popular cryptocurrencies (BTC, ETH, DOGE, etc.)
- 24-hour price change and volume data
- Colored embeds matching price movement
- Alias: !c for quick crypto queries

Uses CoinGecko's free /simple/price endpoint with 30 calls/min rate limit.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -14,6 +14,7 @@ A Discord bot that automatically posts hourly stock price updates for PayPal (PY
 ## Commands
 
 - `!stock <TICKER>` or `!price <TICKER>` - Get current stock price for any ticker
+- `!crypto <SYMBOL>` or `!c <SYMBOL>` - Get current cryptocurrency price (BTC, ETH, etc.)
 - `!market` - Check if NYSE is currently open and view trading hours
 - `!ping` - Check bot responsiveness and latency