fix(python): support @clientDefaultValue on model properties + bump azure-http-specs to 0.1.0-alpha.40-dev.6

[Copilot]

@clientDefaultValue on model properties was silently ignored by the Python emitter — the decorator's values were never forwarded to the code model, so generated models used Optional[T] = None instead of the correct default, and the SDK omitted those fields from serialized request bodies.

Root cause

emitProperty in emitter/src/types.ts did not include clientDefaultValue in its output (unlike the HTTP parameter path in http.ts, which handled it correctly).

Changes

• emitter/src/types.ts — add clientDefaultValue: property.clientDefaultValue to emitProperty return value so model property defaults flow through to the code model.
• package.json — bump @azure-tools/azure-http-specs 0.1.0-alpha.39 → 0.1.0-alpha.40-dev.6, which includes the mock fix from Fix client-default-value mock to always include client defaults in request Azure/typespec-azure#4300 (PUT body now requires client defaults, exposing the bug above).

Effect on generated code

Before:

class ModelWithDefaultValues(_Model):
    timeout: Optional[int] = rest_field(visibility=[...])
    tier: Optional[str] = rest_field(visibility=[...])
    retry: Optional[bool] = rest_field(visibility=[...])

    def __init__(self, *, name: str, timeout: Optional[int] = None, ...) -> None: ...

After:

class ModelWithDefaultValues(_Model):
    timeout: int = rest_field(visibility=[...], default=30)
    tier: str = rest_field(visibility=[...], default="standard")
    retry: bool = rest_field(visibility=[...], default=True)

    def __init__(self, *, name: str, timeout: int = 30, tier: str = "standard", retry: bool = True) -> None: ...

ModelWithDefaultValues(name="test") now serializes to {"name": "test", "timeout": 30, "tier": "standard", "retry": true} as expected.