#235 Comprehensive OpenAPI documentation for all 159 API endpoints

Complete OpenAPI/Swagger documentation coverage for all API endpoints. ## Current Status - Infrastructure: Done (#224) - Workflows: 11 endpoints (response validation disabled - #234) - Auth: 23 endpoints done (#227) ## Remaining Tickets - #226: Core Execution (24 endpoints) - #228: Infrastructure & Monitoring (19 endpoints) - #229: Analytics & Reporting (17 endpoints) - #230: Administration (15 endpoints) - #231: DSL & Templates (13 endpoints) - #232: Events & Signals (10 endpoints) - #233: SDK Code Generation ## Requirements 1. Add @spec.validate decorators to all endpoints 2. Create Pydantic models for request/response validation 3. Fix UUID serialization issue (#234) 4. Test all endpoints in Swagger UI 5. Generate TypeScript/Python SDK (#233) ## Total: ~159 endpoints across 33 blueprint files Also add membership requirements (RBAC) for each api