feat(tracer): show elapsed time on message cards and sidebar rounds (#100)

Add per-message elapsed time ("Took X ms") to playground message cards (#99)

Fix: Playground streaming output does not auto-scroll to bottom (#97)

Add `created_at` timestamps to UniMessage/UniEvent, round tracking in Tracer, gpt-5.2→gpt-5.4 (#96)

Move cache_control from message content items to top-level API parameter (#95)

Bump versions to 0.3.1-dev, add PyPI/npm environment URLs, readme and license to Python package (#94)

chore: bump version to 0.3.0 and prepare release (#93)

Update CHANGELOG and model name in README (#92)

Migrate to the latest GPT-5.4 model (#87)

Replace `<pre>` tags with Tailwind CSS, make Tools textarea resizable, add collapsible config and auto-resizing message input (#86)

Fix thinking display order in playground, add GitHub attribution links, gate slow provider tests behind RUN_SLOW_TEST (#84)

Add Claude 4.6 client, support adaptive thinking, and vertex ci (#82)

Add KimiK2_5Client and sync all model clients between Python and TypeScript (#81)

Defer history mutation in `streaming_response_stateful` until inference succeeds (#80)

Add AWS Bedrock Claude Messages API usage guide and Bedrock client support (#79)