Enable PDF files to be previewed directly in the file content panel
instead of showing as unsupported files requiring download. Uses the
existing react-pdf-highlighter library with zoom controls and keyboard
shortcuts (up/down arrows).
Add a unified isPreviewable flag to useFileTypeInfo that guards against
rendering binary files as text in both skill artifacts and variable
inspect artifacts preview. Upgrade extension arrays to Sets for O(1)
lookups.
Implement ReadOnlyFilePreview to render sandbox files by type
(code, markdown, image, video, SQLite, unsupported) using existing
skill viewer components with readOnly support. Add
useSandboxFileDownloadUrl and useFetchTextContent hooks for data
fetching, and generalize useFileTypeInfo to accept any file-like
object.
