Changes

PR #1884 by ksylvan: Implement interactive Swagger API documentation and automated OpenAPI specification generation

• Add Swagger UI at /swagger/index.html endpoint
• Generate OpenAPI spec files (JSON and YAML)
• Document chat, patterns, and models endpoints
• Update contributing guide with Swagger annotation instructions
• Add swaggo dependencies to project

PR #1880 by ksylvan: docs: add REST API server section and new endpoint reference

• Add README table-of-contents link for REST API
• Document REST API server startup and capabilities
• Add endpoint overview for chat, patterns, contexts
• Describe sessions management and model listing endpoints
• Provide curl examples for key API workflows