[Bug]: Trace: align dictionary value annotations across its properties

Describe the bug

Trace.metadata, Trace.inputs, and Trace.outputs getters declare dict[str, str] | None, and their setters declare string-only dictionary values. Normal Trace construction and updates support numeric, nested, and other non-string values; the getters return those values unchanged.

The underlying Span.attributes and Result.inputs/outputs use dict[str, Any] | None. The Trace constructor's own example includes numeric metadata, whereas the property annotations imply every retrieved value is a string.

Minimal reproduction

from wandb.sdk.data_types.trace_tree import Trace

trace = Trace(
    "example",
    metadata={"attempts": 2},
    inputs={"x": [1, 2]},
    outputs={"score": 0.9},
)
print(trace.metadata)  # {'attempts': 2}
print(trace.inputs)    # {'x': [1, 2]}
print(trace.outputs)   # {'score': 0.9}

if trace.metadata is not None:
    trace.metadata["attempts"].upper()

The final operation raises AttributeError: 'int' object has no attribute 'upper', contradicting the declared string-valued return. No logging, login, or server is involved.

Expected behavior

Align these related getter/setter value annotations with the dictionaries supported by the Trace API.

Environment

• W&B SDK: 0.30.0; relevant source is identical on main 8f93d444e29e4d1a50a888899f51051012ee2679
• Python: 3.12.12
• OS: macOS 26.1, arm64
• W&B server: not applicable