docs: update API documentation, static OpenAPI file, and Swagger/Redoc display

[coolert]

PR Summary

This PR updates the API documentation presentation, introduces a static OpenAPI
file for both local and production Swagger/Redoc views, and removes the previous
Laravel route used for serving openapi.yaml.

These changes ensure a consistent, production-ready API documentation experience.

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Changes

OpenAPI

• Updated docs/openapi/openapi.yaml with the correct production server:
  • https://api.task.coolerk.com

README

• Added live production documentation links:
  • Swagger → https://api.task.coolerk.com/swagger.html
  • Redoc → https://api.task.coolerk.com/redoc.html
• Updated local documentation URLs for consistency.

Public Assets

• Added public/openapi/openapi.yaml to allow Swagger/Redoc to load specs without
  relying on Laravel routing.
• Updated public/swagger.html to load "/openapi/openapi.yaml".
• Updated public/redoc.html accordingly.

Routes

• Removed old /openapi.yaml Laravel route that previously served the spec file.

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Type of Change

• Feature
• Fix
• Docs
• Refactor
• CI
• Other