feat: add UnrecognizedEvent and raw_json() to the webhook event

[razor-x]

Stacked on #653. Retarget to main once that merges.

The hole

An event whose event_type this SDK version does not know deserialized to a DeepAttrDict, where a missing key raises AttributeError rather than reading as None:

ev = seam_event_from_dict({"event_id": "e", "event_type": "future.thing"})
ev.event_id      # 'e'
ev.event_type    # 'future.thing'
ev.workspace_id  # AttributeError   <-- explodes
ev.created_at    # AttributeError
ev.occurred_at   # AttributeError

A handler reading a field every event shares worked for every event type the SDK knows and threw on the ones it does not — exactly backwards. Python was the only SDK with this behavior; Ruby, PHP, C# and JS all return null, because their fallback is a class declaring the shared event fields.

The fix

UnrecognizedEvent, built from the generic event resource the blueprint already carries, with every shared field optional. UnrecognizedActionAttempt does the same for an unrecognized action_type or status — there is no generic action_attempt resource in the blueprint, so it is built from the properties every variant agrees on.

ev.workspace_id  # None
isinstance(ev, UnrecognizedEvent)  # True

Why raw_json() is in the same PR

This drops ad-hoc access to fields the SDK does not know, which DeepAttrDict allowed. Three existing tests asserted exactly that (event.future_field.nested, unknown.future_api_field, event.foo.bar) and are updated here.

That trade is intended — writing logic against a new field is what an upgrade is for — but it would be a pure capability loss without a way to reach the payload. So events also gain raw_json():

json.loads(event.raw_json())["a_field_this_version_predates"]

Scoped to events, for the webhook verify return; a test asserts Device does not have it. A method rather than a property because the call is where the serialization happens. The retained payload is repr=False and compare=False, so it changes neither the repr nor equality.

What is deliberately not changed

The declared SeamEvent and ActionAttempt unions. Adding an all-optional member would make every field on them optional for type checkers — action_attempt_id becoming str | None alone produced 14 mypy errors in this repo, and would produce more in callers. The fallback is returned via cast, and isinstance is how you detect it.

282 tests, mypy clean, pylint 10.00, black clean.

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https://claude.ai/code/session_01M2kJ4nGaM8imZCVMEKjmXA

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