feat: make DigitalOcean API token optional at server startup

[naikmubashir]

Fixes #103

Description

This PR resolves issue #103 by making the DigitalOcean API token optional at server startup. The MCP server can now start successfully without a token and provides helpful error messages when API calls are made without proper authentication.

Changes Made

Core Server Changes

• Modified cmd/mcp-digitalocean/main.go: Removed mandatory token validation during server initialization
• Added warning message: Server displays clear warning when starting without token
• Maintained backward compatibility: Existing token configurations work exactly as before

Documentation Updates

• Updated README.md: Added "API Token Configuration" section explaining optional token behavior

Testing

Manual Testing

• Server starts successfully without token (shows warning, doesn't exit)
• Server starts normally with valid token
• API calls without token provide helpful error messages
• API calls with valid token work as expected
• Backward compatibility maintained

Test Commands

# Server starts without token (shows warning)
npx @digitalocean/mcp --services apps

# Server works normally with token
DIGITALOCEAN_API_TOKEN=your_token npx @digitalocean/mcp --services apps

# Go binary works without token
go run ./cmd/mcp-digitalocean --services accounts

Signed-off-by: Naik Mubashir naikmubashir095@gmail.com

[thearyanahmed]

Suggested change

	if token == "" {
	logger.Warn("DigitalOcean API token not provided. Server will start but API calls will fail until token is available. Use --digitalocean-api-token flag or set DIGITALOCEAN_API_TOKEN environment variable")
	// Create a client with empty token - this will allow server to start but API calls will fail
	client, err = newGodoClientWithTokenAndEndpoint(context.Background(), "", endpoint)
	} else {
	client, err = newGodoClientWithTokenAndEndpoint(context.Background(), token, endpoint)
	}
	if token == "" {
	logger.Warn("DigitalOcean API token not provided. Server will start but API calls will fail until token is available. Use --digitalocean-api-token flag or set DIGITALOCEAN_API_TOKEN environment variable")
	}
	client, err := newGodoClientWithTokenAndEndpoint(context.Background(), token, endpoint)

This should have the same outcome with lesser nesting.

[thearyanahmed]

As per the conflict, we want to handle both scenarios, http and stdio transports.