feat: implement Google Drive integration and enhance documentation for new features

docs/ConfigurationTroubleshooting.md

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+# Configuration Troubleshooting Guide
+
+This guide helps you resolve common configuration issues with DocuNova's various integrations.
+
+## SMTP Email Configuration
+
+### Common Error: "Name or service not known"
+
+This error occurs when the system can't resolve the hostname of your SMTP server.
+
+**Solutions:**
+1. Verify the `EMAIL_HOST` value in your `.env` file is correct
+2. Check that your DNS is working properly:
+   ```bash
+   nslookup your-smtp-server.com
+   ```
+3. If running in Docker, verify the container has network access
+4. Try using an IP address instead of a hostname
+
+### Common Error: "Connection refused"
+
+This error indicates the SMTP server is unreachable on the specified port.
+
+**Solutions:**
+1. Verify `EMAIL_PORT` is correct (typically 587 for TLS, 465 for SSL)
+2. Check if the email server is running and accessible from your network
+3. Test connectivity using telnet:
+   ```bash
+   telnet your-smtp-server.com 587
+   ```
+4. Check firewall settings to ensure the port is open
+
+## Storage Provider Configuration
+
+### Missing Configuration Attributes
+
+When you see errors like "Settings object has no attribute 'nextcloud_url'" or similar:
+
+**Solutions:**
+1. Make sure all required environment variables are defined in your `.env` file
+2. Check for typos in variable names
+3. Ensure the application has loaded the environment variables
+4. Restart the application after making changes to environment variables
+
+### Example Configuration for Common Providers
+
+#### Dropbox
+```
+DROPBOX_TOKEN=your_oauth2_token
+DROPBOX_FOLDER=/DocuNova
+```
+
+#### Nextcloud
+```
+NEXTCLOUD_URL=https://your-nextcloud-instance.com
+NEXTCLOUD_USERNAME=your_username
+NEXTCLOUD_PASSWORD=your_secure_password
+NEXTCLOUD_FOLDER=/Documents
+```
+
+#### SFTP
+```
+SFTP_HOST=your-sftp-server.com
+SFTP_PORT=22
+SFTP_USERNAME=your_username
+# Use either password or key authentication:
+SFTP_PASSWORD=your_secure_password
+# Or:
+SFTP_PRIVATE_KEY=/path/to/private_key.pem
+SFTP_PRIVATE_KEY_PASSPHRASE=optional_passphrase
+SFTP_FOLDER=/upload/path
+```
+
+## Testing Configuration
+
+You can use the configuration validator to test your settings:
+
+```bash
+# Inside the container:
+python -c "from app.utils.config_validator import check_all_configs; check_all_configs()"
+```
+
+## Debugging Tips
+
+1. Check the application logs for specific error messages
+2. Verify network connectivity from your application server to the external services
+3. Ensure all required credentials are correct and access permissions are properly set
+4. For OAuth services (like Dropbox), verify the token has not expired
+5. If using Docker, check that environment variables are properly passed to the container