Add APS OAuth 2.0 Authentication Client

[LeonardNoh]

Summary

Implement complete APS Authentication API client with OAuth 2.0 support, token management, and HTTP client utilities.

What's New

• OAuth 2.0 Flows: 2-legged (Client Credentials) and 3-legged (Authorization Code with PKCE)
• Token Management: Automatic caching, refresh, revoke, and logout
• Token Storage: Abstract interface with thread-safe in-memory implementation
• HTTP Client: Retry logic, pagination helper, presigned/signed URL upload support
• Complete Scopes: All APS OAuth scopes including OpenID, Data Management, Buckets, ACC, Design Automation
• Comprehensive Examples: Working smoke tests demonstrating all API flows

Key Features

• ✅ PKCE (RFC 7636) support for enhanced security
• ✅ Automatic token expiration handling with 30s skew
• ✅ Flexible caching strategy with scope-based keys
• ✅ Thread-safe token storage with RLock
• ✅ Multiple response modes: json/text/raw/stream
• ✅ Auto-refresh for 3-legged tokens

Files Changed

• src/pyaps/auth/client.py (486 lines) - Main OAuth client implementation
• src/pyaps/auth/token_store.py (105 lines) - Token storage abstraction
• src/pyaps/auth/example.py (316 lines) - Comprehensive usage examples
• src/pyaps/http/client.py (193 lines) - HTTP client with APS-specific helpers

Testing

Run the examples to see all features in action:

export APS_CLIENT_ID='your_client_id'
export APS_CLIENT_SECRET='your_client_secret'
python3 -m pyaps.auth.example
Example Usage
from pyaps.auth.client import AuthClient, Scopes
from pyaps.auth.token_store import InMemoryTokenStore

# 2-legged OAuth
client = AuthClient(
    client_id="...",
    client_secret="...",
    store=InMemoryTokenStore()
)
token = client.two_legged.get_token([Scopes.DATA_READ, Scopes.BUCKET_READ])

# 3-legged OAuth with PKCE
verifier, challenge = client.three_legged.generate_pkce_pair()
auth_url = client.three_legged.build_authorize_url(
    scopes=[Scopes.DATA_READ, Scopes.USER_PROFILE_READ],
    code_challenge=challenge
)
# After user authorizes...
token = client.three_legged.exchange_code(code, code_verifier=verifier)
Total Changes
5 files changed
1,100+ lines added
0 lines deleted