Add comprehensive OpenAPI 3.0 documentation for the API

[Copilot]

This PR adds complete OpenAPI 3.0 documentation for the Home Access Center API, making it easy for developers to understand and integrate with all available endpoints.

📚 What's Added

OpenAPI Specification (openapi.yaml)

A complete OpenAPI 3.0.3 specification documenting all 13 endpoints:

Student Information

• GET /api/name - Retrieve student's full name
• GET /api/info - Get detailed student profile (grade, school, DOB, counselor, etc.)

Classes & Grades

• GET /api/classes - List all enrolled classes
• GET /api/averages - Current grade averages
• GET /api/assignments - Detailed assignment information with grades
• GET /api/weightings - Grade category weightings
• GET /api/gradebook - Complete gradebook (combines averages, assignments, and weightings)

Reports

• GET /api/reportcard - Official report cards
• GET /api/ipr - Interim progress reports
• GET /api/transcript - Full academic transcript with GPA
• GET /api/rank - Class rank and quartile information

The specification includes:

• Complete request/response schemas with examples
• All query parameters (user, pass, link, short, six_weeks, no_cache)
• Proper error responses (401 Unauthorized, 500 Internal Server Error)
• Server configurations for both production and local development
• Organized tags and descriptions for easy navigation

Interactive Documentation (docs.html)

A beautiful, standalone HTML documentation page that works offline without external CDN dependencies. Features:

• Clean, modern UI with proper styling
• Organized by endpoint categories
• Usage examples with curl commands
• Cache information and tips
• Links to OpenAPI spec and external tools

Documentation Guide (API_DOCUMENTATION.md)

Comprehensive guide covering:

• How to view documentation locally
• Integration with popular tools (Swagger Editor, Postman, Insomnia, VS Code, Redocly)
• Quick start examples
• Contributing guidelines for maintaining documentation

Enhanced README

Updated README.md with:

• API documentation section with links to all resources
• Complete endpoint listing organized by category
• Query parameters documentation
• Usage examples

🎯 Benefits

1. Developer Experience: Developers can now understand all available endpoints at a glance
2. Tool Integration: Import openapi.yaml into Postman, Insomnia, or Swagger for instant API collections
3. Standards Compliance: Following OpenAPI 3.0.3 standard ensures compatibility with the ecosystem
4. Quick Reference: docs.html provides immediate access to formatted documentation
5. Maintainability: Clear structure makes it easy to update documentation as the API evolves

✅ Validation

• OpenAPI specification validated with swagger-cli ✓
• All endpoints from source code verified present in documentation ✓
• HTML documentation tested and renders correctly ✓
• No build artifacts or temporary files committed ✓

🚀 How to Use

Quick View:

# Open HTML documentation in browser
open docs.html

With Swagger Editor:

1. Visit editor.swagger.io
2. Import openapi.yaml
3. View interactive documentation and test endpoints

With Postman/Insomnia:

1. Import openapi.yaml
2. All endpoints automatically added as a collection

With Redocly:

npm install -g @redocly/cli
redocly preview-docs openapi.yaml

Closes issue requesting OpenAPI documentation for the API.

Original prompt

document this api with openapi

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