Edit Issue - .issue.db

Title *

Description

## Overview
Set up OpenAPI 3.0 specification infrastructure for Highway Workflow Engine API.

## Current State
- 159 API endpoints across 33 blueprint files
- No OpenAPI/Swagger implementation exists
- Using Quart (async Flask) framework
- Pydantic 2.0+ already installed

## Requirements

### 1. Choose and Install OpenAPI Library
Options for Quart:
- **quart-schema** - Quart-native, good Pydantic support
- **spectree** - Modern, works with Quart/Flask, excellent Pydantic 2.0 support
- **apispec** + **apispec-webframeworks** - Generic, requires more manual work

**Recommendation:** spectree with Pydantic for automatic schema generation

### 2. Create Base Infrastructure
```python
# api/openapi/__init__.py
from spectree import SpecTree

spec = SpecTree(
    'quart',
    title='Highway Workflow Engine API',
    version='1.0.0',
    path='openapi',  # /openapi/redoc, /openapi/swagger
    security_schemes=[
        {'name': 'Bearer', 'type': 'http', 'scheme': 'bearer'}
    ]
)
```

### 3. Create Base Response/Request Models
```python
# api/openapi/models/base.py
from pydantic import BaseModel

class SuccessResponse(BaseModel):
    status: str = 'success'
    data: dict | list | None = None

class ErrorResponse(BaseModel):
    status: str = 'error'
    message: str
    code: str
```

### 4. Set Up Swagger UI and ReDoc
- /api/v1/docs (Swagger UI)
- /api/v1/redoc (ReDoc)
- /api/v1/openapi.json (Raw spec)

## Files to Create
- api/openapi/__init__.py
- api/openapi/models/__init__.py
- api/openapi/models/base.py
- api/openapi/models/common.py (pagination, errors)

## Dependencies to Add
```toml
spectree>=1.0.0
```

## Acceptance Criteria
- [ ] OpenAPI library integrated with Quart app
- [ ] Swagger UI accessible at /api/v1/docs
- [ ] ReDoc accessible at /api/v1/redoc
- [ ] Base response models created
- [ ] Authentication scheme documented
- [ ] All existing endpoints still work

Due Date (YYYY-MM-DD)

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Edit Issue #224