feat: Add React Query hooks for HackerNews API migration (Phase 1)

[devin-ai-integration]

feat: Add React Query hooks for HackerNews API (Phase 1)

Summary

Converts the Angular HackerNewsAPIService to custom React hooks using TanStack Query (@tanstack/react-query) as part of the Angular-to-React migration. This is Phase 1 — hooks only, no wiring to components yet.

New files (all under src/hooks/):

• types.ts — TypeScript interfaces mirroring the existing Angular models (Story, User, PollResult, Comment, FeedType)
• useFeed.ts — fetches feed listings by type and page
• useItem.ts — fetches an item; includes poll aggregation logic (fetches poll options via Promise.all and sums poll_votes_count)
• useUser.ts — fetches user profiles
• usePollResults.ts — fetches individual poll result items
• index.ts — barrel export

RxJS Observables and lazyFetch are replaced with async/await + React Query's useQuery. Poll logic from the Angular service is preserved: for poll-type stories, poll options are fetched in parallel using story.id + i for i in 1..poll.length.

Review & Testing Checklist for Human

• @tanstack/react-query is NOT installed — package.json was not modified. Confirm this is acceptable for Phase 1, or whether the dependency should be added now so the files at least compile
• Poll ID arithmetic in useItem.ts (lines 26-27): verify story.id + i for i in 1..numberOfPollOptions matches the original Angular behavior and API expectations
• BASE_URL is hardcoded in each hook file — decide if this should be extracted to a shared constant before later phases build on top of this
• No unit tests — consider whether tests should be added in this phase or deferred

Notes

• The crated_time typo in the User interface is intentionally preserved from the original Angular model (src/app/shared/models/user.ts)
• Story.time_ago is typed number (matching the original Angular class) while Comment.time_ago is string — this discrepancy exists in the original codebase
• These hooks cannot be tested end-to-end until React and React Query are installed in a later phase

Requested by: @eashansinha
Link to Devin run: https://app.devin.ai/sessions/a63f2fb87f504e82991177c18bdcadc8

[devin-ai-integration]

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