Check if a value is a SignalStruct.
Create a new SignalStruct with an initial value.
The initial struct value
Log every struct-level mutation call on a SignalStruct at Debug
level, tagged under the stax.signal subsystem, with the call site
captured at the caller's frame.
The write-side counterpart to Readable.debug, for SignalStruct.
Wraps update and replace — the struct-level mutations. Field
signals (struct.name.set(...) etc.) are plain Signals and can be
traced individually with Signal.trace if needed.
Zero cost at the default log level — the check runs once at construction and returns the underlying signal unwrapped if Debug isn't enabled.
SignalStruct namespace.