feat: add declarative reconnect flag with transport-factory auto-disable

[GregHolmes]

Summary

Adds a new reconnect: bool = True kwarg to DeepgramClient and AsyncDeepgramClient. When a custom transport_factory is provided, reconnect is auto-set to False to signal that the custom transport owns its own retry/reconnect lifecycle.

Why

Custom transports (e.g., the SageMaker transport in deepgram-python-sdk-transport-sagemaker) implement their own retry and reconnect logic — full-jitter backoff, retry-budget windows, replay buffers, etc. Stacking SDK-level retries on top of that would cause storm-on-storm behavior under burst load, which is the failure mode that motivated this parity work across the SDKs.

This adds an explicit, declarative way to express "the SDK is not responsible for reconnects." Today the Python SDK has no wrapper reconnect layer (the websockets library doesn't auto-reconnect; transports manage their own), so the flag is declarative only: it documents intent and reserves the slot for any future SDK-side reconnect logic.

Parity with other SDKs

• Mirrors the reconnect parity work in deepgram-java-sdk
• Same flag added to deepgram-js-sdk in PR Python SDK examples websocket async_http bug #492 (gh/pluggable-transport-sagemaker)

Behavior

# Default — reconnect=True, no custom transport: SDK behaves as before
client = DeepgramClient(api_key="...")
assert client.reconnect is True

# Custom transport — reconnect auto-disabled to False
client = DeepgramClient(api_key="...", transport_factory=my_factory)
assert client.reconnect is False

# Explicit opt-in even with custom transport — caller takes responsibility
client = DeepgramClient(
    api_key="...",
    transport_factory=my_factory,
    reconnect=True,
)
assert client.reconnect is True

Test plan

Covered in tests/custom/test_transport.py:

• Default state: client.reconnect == True
• Explicit reconnect=False is respected
• transport_factory auto-disables → reconnect == False
• Explicit override transport_factory=..., reconnect=True is respected

Release impact

• feat: → minor version bump per release-please conventions
• Fully backwards-compatible — new optional kwarg with sensible default; existing callers need no change
• No regen impact: hand-written patch to src/deepgram/client.py, already in .fernignore