React migration: ItemDetails + CommentItem components

[devanshi-gpta]

Summary

Ports the Angular ItemDetailsComponent and recursive CommentComponent to React, replacing the existing stubs.

• ItemDetails.tsx: fetches a story via fetchItemContent(itemID) in a useEffect keyed on itemID (with window.scrollTo(0,0)), rendering <Loader /> while pending and <ErrorMessage message="Could not load item comments." /> on failure. Preserves the original template structure: mobile header with a back button (navigate(-1)), laptop header (conditional item-header/head-margin classes), poll results with pollBar width points/poll_votes_count*100%, subject via dangerouslySetInnerHTML, and a comment-list of <CommentItem />. External-vs-internal title link keys off hasUrl = item.url.indexOf('http') === 0; openLinkInNewTab from useSettings() controls target/rel.
• CommentItem.tsx: recursive component with local collapse state. Renders [+]/[-] toggle, user <Link>, time_ago, comment-text (innerHTML), and recurses over comment.comments into a subtree. Deleted comments render the [deleted] meta. Named CommentItem to avoid clashing with the Comment model type.
• SCSS ported verbatim from the Angular component styles with @import paths rebased to ../shared/scss/... and :host >>> wrappers dropped.

npm run build (tsc + vite) and npm run lint both pass with no errors/warnings. No files outside src/item-details/ were touched.

Link to Devin session: https://app.devin.ai/sessions/f2735a4278f142dcb87cb5c2422a3edb
Requested by: @devanshi-gpta

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