[6.x] Inertia asset index

[brianjhanson]

Ports the Asset index to Inertia/Vue and, along the way, extracts a shared element-index pipeline that the entries index now rides on as well.

• Shared index pipeline — consolidates per-element-type index rendering onto a ContentIndexViewModel base, with AssetIndexViewModel and EntryIndexViewModel on top. AssetsIndexController renders assets/Index and ContentIndexController renders content/Index from the same payload. The Vue side mirrors this with an ElementIndexPage component and useElementIndexPage / useElementIndexTable / useContentIndexData composables.
• Asset folders & navigation — the index payload now carries folders, breadcrumbs, and thumbnail data. Folders render inline in the table with click-to-navigate (useFolderNavigation), navbar breadcrumbs gain an optional action menu, and a "New subfolder" breadcrumb action creates folders (useNewSubfolder).
• Drag-and-drop moving — assets can be dragged onto folder rows and breadcrumb targets to move them (useAssetMoveDrag / assetMover), with the payload exposing folder and breadcrumb move targets and selection restored once the drag ends.
• Thumbnail view — a card/thumbnail grid (ElementThumbs) for asset sources.
• craft-truncate component — a new @craftcms/ui component for truncating labels with an overflow tooltip, replacing craft-element-label for thumbnail and chip labels (the legacy CraftElementLabel now renders through it).
• Plugin boot ordering — plugins are loaded after the database is booted, so index sources backed by plugin-registered element types resolve correctly.

Related issues

CMS-2281

[github-actions]

📚 Storybook previews

@craftcms/ui — open Storybook

Changed components:

• Components/Chip
• Components/Indicator
• Components/Indicator
• Components/Truncate

resources/js — open Storybook

No changed components detected in this Storybook.