* Python: surface Gemini cached and thinking token counts in usage details
* Python: surface Bedrock cache token counts in usage details
* Python: surface Gemini cached and thinking token counts in usage details
* Python: surface Bedrock cache token counts in usage details
* Return None from Bedrock _parse_usage when no token counts are present
Matches the UsageDetails | None return annotation and the Gemini
connector's behavior, so a usage payload with no recognized keys no
longer propagates an empty mapping. Adds a regression test.
Yufeng He
1df47667ea