feat(bedrock): emit streaming latency span attrs

[sayonfortify]

Adds FortifyRoot streaming latency span attributes for Bedrock streaming paths.

• Sets fortifyroot.llm.streaming.time_to_first_token_ms and fortifyroot.llm.streaming.time_to_generate_ms on Invoke-with-response-stream and ConverseStream spans.
• Measures request-start -> first text and first text -> completion using the existing streaming wrappers.
• Leaves attrs absent for empty streams/non-streaming calls; no fake zero values.
• Keeps existing safety masking, guardrail, usage, prompt-caching, event emission, and span-end behavior intact.
• Adds deterministic unit coverage for Invoke and Converse wrappers, including empty-stream omission.

Validation:

• python3 -m py_compile for changed Bedrock source/test files
• PYTHONPATH=packages/opentelemetry-instrumentation-bedrock:packages/opentelemetry-instrumentation-fortifyroot:packages/opentelemetry-semantic-conventions-ai conda run -n py3.12 python -m pytest packages/opentelemetry-instrumentation-bedrock/tests/test_safety_hooks.py -q
  • 22 passed
• git diff --check clean

Next per vendoring SOP after merge: tag the fork, then run ocelle-py/scripts/vendor.sh from the tag before the Ocelle vendored PR.