## What kind of change does this PR introduce?
follow-up to #50235 to reduce reference page payloads and cold rendering
overhead
## What is the current behavior?
reference pages ship a large rsc payload inside the html _ most of it is
duplication rather than content along with shiki that writes ~30
character css variable name for every syntax token making the page heavy
in some cases
## What is the new behavior?
- moves repeated styles into shared css and uses compact, namespaced
token classes
- renders details icons inside the client trigger
- follows shiki’s guidance to [reuse one
highlighter](https://shiki.style/guide/best-performance#cache-the-highlighter-instance)
and [load languages on
demand](https://shiki.style/guide/best-performance#use-shorthands)
`page size`
page | before | after | change
-- | -- | -- | --
javascript | 10.61 mb | 8.28 mb | -21.9%
dart | 4.59 mb | 4.13 mb | -10.1%
python | 4.38 mb | 3.73 mb | -14.9%
swift | 2.87 mb | 2.56 mb | -10.9%
server | 1.59 mb | 1.35 mb | -15.2%
kotlin | 3.42 mb | 3.17 mb | -7.2%
`cold initialization`
language | before | after | reduction
-- | -- | -- | --
bash | 2,180 ms | 23 ms | 98.95%
javascript | 2,245 ms | 38 ms | 98.29%
## Additional context
measured on a local production build which uses the checked in generated
content _ production has larger sdk data, so absolute sizes there will
be higher
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added reusable expand/collapse controls for API reference details,
with updated icons, labels, and styling.
* Improved code block rendering with class-based syntax highlighting,
wrapped-code support, responsive layouts, and lazy language loading.
* **Style**
* Added theme-aware syntax-token colors, line-number styling, and
configurable code-block shadows.
* Consolidated expandable reference panel and item styling.
* **Tests**
* Added coverage for syntax highlighting, code block rendering, language
support, token stability, and reference details.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Anthony Lio