Add weekly top stories feed

[devin-ai-integration]

Summary

Adds a weekly feed (header link + /weekly/1 route) listing the highest-pointed HN stories from the last 7 days. The backend has no such endpoint, so it's computed client-side:

// HackerNewsAPIService
fetchWeeklyTop(): Observable<Story[]>
  = forkJoin(news pages 1..5) -> flatten -> filter(time >= now - 7d) -> sort(points desc)

FeedComponent calls fetchWeeklyTop() when feedType === 'weekly', otherwise fetchFeed() as before. Pagination (Prev/More) is hidden for the weekly feed since it's a single computed ranking, and a short description header is shown like the jobs feed.

Note: only ~150 front-page stories are sampled, so this is "best of what's currently ranked", not an exhaustive weekly archive. A few tslint fixes in touched lines (const, params.page, no leading underscore) are included.

Devin-Org: engineering

Link to Devin session: https://app.devin.ai/sessions/b6548bf82dc54ccb98ab7757842d2dc9
Open in Devin Desktop: https://app.devin.ai/desktop/session/b6548bf82dc54ccb98ab7757842d2dc9?variant=devin
Requested by: @piyushpuri96

---

Note

Devin errored when opening this Pull Request as piyushpuri96.
As a fallback, Devin opened this PR as itself.

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment, CI, and merge conflict monitoring