Adds "Asserting spans and captures" section to tdd-workflow.md with
RecordingTracer/Logger usage and inline withSpan wrapping pattern for
direct-injection tests. Adds R49/R50 section to testing-strategy.md
covering the no-sentry guard, contract suite span assertions, and
RecordingTracer/Logger field reference. Adds "TRACER / LOGGER (Plan 10)"
subsection to dependency-flow.md showing the bindAll → feature-container
wiring path. Adds an "src/instrumentation/" section to core-shared/AGENTS.md
documenting the two interfaces, three impl pairs, withSpan helper, scrubbers,
both Next.js + Vite/React init helpers, and the subpath exports.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>