Add comprehensive sign.html test and update documentation

- Add examples/sign.html with comprehensive extension compatibility testing
- Update README.md with profile fetching API documentation
- Update .gitignore for better file management
- Update examples/button.html and examples/modal.html with latest features

This completes the single-extension architecture implementation with:
- nos2x compatibility through true single-extension mode
- Method switching between extension/local/NIP-46/readonly
- Enhanced profile fetching for floating tab
- Comprehensive debugging and testing capabilities

examples/button.html

@@ -51,7 +51,7 @@
   <script>
     document.addEventListener('DOMContentLoaded', async () => {
       await window.NOSTR_LOGIN_LITE.init({
-        theme: 'default',
+
         methods: {
           extension: true,
           local: true,