feat: add browser-native playground (#3123)
* feat: add browser-native playground
* fix: provision Node for playground CI
* fix: fill playground response column
* fix: omit optional falsy defaults
* fix: initialize optional input inclusion
* fix: check optional null inputs by default
* fix: uncheck optional inputs with defaults
* fix: constrain response body inspector
* fix: improve playground control contrast
* fix: align playground controls with Kumo
* fix: contain CodeMirror scrolling
* fix: preserve complete response collections
* fix: declare Node for playground tests
* chore: simplify playground test tooling
* Remove vendored deps
* fix: run playground tests outside mise
* fix: restore CodeMirror 6 playground editor
* Fix bug with metrics
* fix: bundle playground assets locally
* fix: lock playground toolchain
* fix: isolate playground toolchain
* revert: keep streaming example unchanged
* fix: use mise pnpm backend for playground
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Co-authored-by: Michael Dwan <code@michaeldwan.com>
