Add FastAPI REST interface to SMSgate

[Copilot]

SMSgate only exposed a Twisted XML-RPC API. This adds a parallel FastAPI/uvicorn REST interface that mirrors every XML-RPC operation, with auto-generated OpenAPI docs at /docs.

New: server/fastapi_server.py

Endpoint	Operation
GET /ping	Liveness check
POST /sms/send	Queue outbound SMS
GET /sms/delivery-status/{sms_id}	Poll delivery status
POST /sms/received	Retrieve buffered inbound SMS
POST /ussd/send	Send USSD code
GET /health	Combined pool + SMTP health
GET /stats	Per-modem statistics

• Reuses the same bcrypt token validation and [api] config keys as the XML-RPC server
• Optional TLS via uvicorn ssl_certfile/ssl_keyfile
• create_app() factory is separately importable for testing

Integration (server/smsgate.py)

FastAPI server starts as a daemon thread alongside the Twisted reactor — opt-in via config:

[fastapi]
enabled = True
host = localhost
port = 8000
# certificate = cert.pem  # optional TLS
# key = key.pem

Dependencies (requirements.txt)

Added: fastapi==0.135.2, uvicorn==0.42.0, pydantic==2.12.5, starlette==1.0.0, h11==0.16.0, click==8.3.1, anyio==4.9.0, annotated-types==0.7.0, pydantic_core==2.41.5

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based on the project add new fast api interface