fix(js): preserve <shiny-aside> in Markdown list items

[cpsievert]

Follow up to #278

Why this matters

Rich <shiny-aside> content can follow claims in Markdown lists without changing list structure, corrupting the aside body, or losing document-scoped Markdown behavior.

Previously, the Markdown parser could place an aside opener inside a list item while placing its block body and closing tag outside the list. The resulting raw HTML span caused adjacent list items to nest incorrectly.

What changed

Complete asides opened from list items are normalized to the list item's required continuation indentation before the complete document is parsed again. Keeping the final Markdown in one document parse preserves reference definitions, footnotes, nested-list structure, and relative code indentation without replacing micromark's list tokenizer.

The change also preserves:

• Rich block Markdown inside aside bodies
• Inline aside openers and multi-digit ordered-list markers
• Literal aside markup in code spans and code fences
• Authored custom elements without internal placeholder collisions
• Incomplete tags during streaming
• Existing URL sanitization and React-based rendering

The rebuilt JavaScript assets are included for the Python and R packages.

Verification

• Focused aside/template tests: 19 passed
• Full JavaScript suite: 970 passed, 23 skipped
• npm run lint
• npm run build
• Distributed JS and source-map hashes match across js/dist, Python, and R package assets

[Copilot]

Pull request overview

This PR improves shinychat’s Markdown pipeline so rich <shiny-aside> blocks that are opened from within Markdown list items remain structurally attached to the correct list item. It does this by normalizing the indentation of complete asides discovered in list-item contexts and then re-parsing the full Markdown document so that reference definitions/footnotes and list structure are preserved.

Changes:

• Added a remark plugin that detects complete <shiny-aside>...</shiny-aside> regions opened from list items and rewrites their continuation indentation so the aside body stays inside the list item.
• Integrated the new normalization plugin into the main markdownProcessor pipeline (before remark-rehype).
• Expanded tests to cover list-adjacent rich asides (including nested lists, blockquotes, reference definitions, footnotes, and URL sanitization) and streaming finalization behavior; updated distributed asset version stamps.

Reviewed changes

Copilot reviewed 6 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
pkg-r/inst/lib/shiny/GIT_VERSION	Updates packaged web-asset version stamp for the R distribution.
pkg-py/src/shinychat/www/GIT_VERSION	Updates packaged web-asset version stamp for the Python distribution.
js/tests/markdown/plugins/rewriteAsideTemplate.test.ts	Adds Markdown parsing assertions for list-item asides, nesting, refs/footnotes, and literal-aside-in-code scenarios.
js/tests/chat/AsideGroup.test.tsx	Adds a streaming/non-streaming render test ensuring adjacent list-item asides finalize correctly without corrupting list structure.
js/src/markdown/processors.ts	Wires the new remark normalization step into the main markdown processor.
js/src/markdown/plugins/normalizeAsideMarkdown.ts	Implements the list-item aside indentation normalization + document reparse transformer.

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