Test gaps and decisions that the test audit found #83

The test audit on the test/test-audit-campaign branch found these gaps. They existed before the audit, and the audit did not remove their proof.

Decisions:

• The second parameter of telemetryDev in @telemetry-dev/ai-sdk and @telemetry-dev/tanstack-ai (overrides), and MediaWrapperOverrides, have no caller outside the tests. Two options: document them as public options, or change the tests to decode the OTLP requests from a fetch spy and remove the parameter in a major release.
• postOtlp and maybeGzip are public exports of @telemetry-dev/otel, but only the package itself uses them. A removal is a breaking change.

Coverage:

• No test runs the ai@6 integration through the real ai-v6 dispatcher. Every ai@6 test sends hand-built events.
• These AI SDK paths have no test: the gateway relabel in the ai@7 and media paths, the ai@7 step without onStepStart, executeTool, wrapGenerateVideo, wrapGetBatchStatus, wrapCancelBatch, the transcription duration, the video counts, and the wrapper passthrough without a key.
• The onConfig phase guard in packages/tanstack-ai/src/middleware.ts has no test. Supported engines do not call onConfig after onStart.
• No release check makes sure that each exports and publishConfig.exports target is in the packed tarball.
• The Python core has no wire test for on_error with a server that returns an error.

Python compatibility code:

• The Bedrock, Google GenAI, LiteLLM, and OpenRouter integrations keep fallbacks for span handle methods (capture_masked, record_output_chunk) that each supported core version has. The Anthropic and OpenAI integrations no longer have them.
• CI tests each Python package against the core in this repository, also in the lowest-bounds job. If the telemetry-dev floor of an integration goes below the version that has these handle methods, no test fails.
• In the Python core, CaptureBudget.from_client and the public metrics_recorder parameter of TelemetrySpanProcessor have no caller.