Sync with react.dev @ a3e9466d

[react-translations-bot]

This PR was automatically generated.

Merge changes from react.dev at a3e9466

DO NOT SQUASH MERGE THIS PULL REQUEST!

Doing so will "erase" the commits from main and cause them to show up as conflicts the next time we merge.

[Copilot]

Pull Request Overview

This PR synchronizes documentation and code changes from react.dev, updating API usage patterns and experimental feature flags across multiple components and docs.

• Updated links and documentation references (e.g. Server Components, React Compiler).
• Revised usage of startTransition with async/await and adjusted the ordering of optimistic updates.
• Introduced and standardized experimental and canary version indicators in UI components and sidebar links.

Reviewed Changes

Copilot reviewed 35 out of 35 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/content/reference/rsc/directives.md	Updated documentation link for React Server Components.
src/content/reference/react/useTransition.md	Modified startTransition wrappers to use async/await.
src/content/reference/react/useOptimistic.md	Changed naming from sendMessage to sendMessageAction and updated message ordering.
src/content/reference/react/experimental_*	Replaced with and added version metadata.
src/content/reference/react/addTransitionType.md	Added experimental API documentation for unstable_addTransitionType.
src/content/reference/react-dom/client/hydrateRoot.md	Revised hydrateRoot usage to render explicitly.
src/content/learn/react-compiler.md	Updated compiler docs from beta to RC with corresponding command changes.
src/content/learn/creating-a-react-app.md	Minor text rewording for deployment guidance.
src/content/community/conferences.md	Added new conference events.
src/content/blog/*	Added new blog posts and updated existing posts to reflect newer experimental features.
src/components/PageHeading.tsx	Refactored props to replace canary with a version field and introduced experimental icon support.
src/components/MDX/MDXComponents.tsx	Integrated new Experimental and ExperimentalBadge components.
src/components/MDX/ExpandableCallout.tsx	Added an experimental variant with adjusted styling.
src/components/Layout/Sidebar/SidebarLink.tsx	Extended version prop to include experimental.
src/components/Layout/Page.tsx	Updated metadata handling to use version instead of canary.
src/components/Icon/IconExperimental.tsx	Introduced a new icon component for experimental features.

Comments suppressed due to low confidence (2)

src/content/reference/react/useOptimistic.md:87

• The ordering of optimistic messages has changed (new messages are now prepended instead of appended). Confirm that this ordering change is intentional.

      },

src/content/reference/react-dom/client/hydrateRoot.md:387

• Ensure that passing as the second argument to hydrateRoot is an intentional change from the previous API usage.

const root = hydrateRoot(container, <App />, {