feat(browser): OTel logs pipeline, MapleBrowser.logger and per-session trace sampling - #1145

Confidence 3/5 · needs attention
_{quality 100/100 · no findings · tests covered · risk medium · 2/2 new units observable}

Adds an OTel logs pipeline behind MapleBrowser.logger, per-session trace sampling (tracing.sampleRate) with ot=th;rv on sampled roots, and reports a failure inside an unsampled traced() as its own kept error span. No defect found; safe to merge.

• MapleBrowser.logger queues records and exports them to OTLP /v1/logs
• SessionSampler decides per session and stamps ot=th;rv on sampled roots
• traced() reports an unsampled failure through captureException
• New tracing.sampleRate, clamped by the shared resolveSampleRate

_{43a9cc9 · Updated on every push. Reply "won't fix" to dismiss a finding, or mention @maple to ask about one.}