feat: Add zap command for sending Bitcoin Lightning tips

- Implemented the `zap` command in the CLI to allow users to send sats to a user, event, or snippet using a NIP-60 wallet.
- Created a new `zap.ts` file to handle the command logic and integrated it into the MCP server.
- Added wallet balance command to check the balance of a user's wallet.
- Enhanced the MCP server to register the new zap command and wallet balance command.
- Introduced caching for wallets to optimize performance and reduce redundant network requests.
- Updated database schema to include snippets table for storing code snippets.
- Improved logging functionality for better debugging and tracking of operations.
- Added functionality to save snippets to the database upon retrieval.
- Updated project overview documentation to reflect new features and structure.
- Refactored existing commands and logic for better modularity and maintainability.

lib/nostr/utils.ts

@@ -6,6 +6,10 @@ import { toPubkeys, toSnippet } from "../converters/index.js";
 
 export const SNIPPET_KIND = 1337;
 
+export function getUsernameFromPubkey(pubkey: string): string | null {
+    
+}
+
 /**
  * Gets the appropriate signer based on the username
  * @param username Username to get signer for (or "main" for default)