Add W&B integration for TraceML end-of-run summaries #49
Description
Add Weights & Biases (W&B) integration so TraceML summaries can be logged into existing experiment tracking workflows.
Scope:
- log end-of-run summary metrics to a W&B run
- upload full TraceML summary as JSON artifact/file
- keep metric names stable for easy run comparison
Why:
Many users already use W&B. This lets TraceML fit into existing workflows instead of requiring a separate dashboard.
Acceptance criteria:
- TraceML summary metrics appear in W&B
- full summary can be uploaded as JSON
- integration is optional
- failure is graceful when W&B is not installed
- metric schema is documented