feat: add MCP tools for integration management

[perasperaactual]

Overview

Add MCP tools to discover, list, and scaffold integrations from stackwright.yml for AI agent consumption.

Motivation

Otter agents need to discover available integrations and scaffold new ones. This enables the full AI → working code workflow without manual YAML editing.

Acceptance Criteria

• stackwright_list_integrations tool - lists all configured integrations
• stackwright_get_integration tool - gets details of specific integration
• stackwright_add_integration tool - scaffolds new integration config
• Tools read from stackwright.yml in project root
• Tools return structured JSON for AI consumption
• Add to existing MCP server in packages/mcp-server
• Comprehensive tests for all tools

Implementation Details

Tool Signatures:

stackwright_list_integrations:

{
  projectRoot?: string
} → {
  integrations: Array<{type, name}>,
  count: number
}

stackwright_get_integration:

{
  name: string,
  projectRoot?: string
} → {
  integration: IntegrationConfig
}

stackwright_add_integration:

{
  type: string,
  name: string,
  config: Record<string, unknown>,
  projectRoot?: string
} → {
  success: boolean
}

Files to Create

• packages/mcp-server/src/tools/integrations.ts (new)
• packages/mcp-server/test/integrations.test.ts (new)

Files to Modify

• packages/mcp-server/src/index.ts (register tools)

Dependencies

Depends on integration schema being merged first

Estimated Time

3-4 hours