[News] Preserve source filter across responsive layout changes #16

The News source filter resets when the responsive layout remounts the page. A reader viewing one publisher unexpectedly returns to all publishers after narrowing the window.

Reproduction:

1. Open /market/news in the current local preview at 1440px width.
2. Select cls in the News source dropdown and wait for the 财联社 reports.
3. Resize the viewport to 375px width and allow the responsive layout to settle.
4. The dropdown changes to All sources (value: "") and the stream includes other publishers. Important events also reflect the broader source scope.

Expected: retain the selected source across responsive layout changes, or persist it in the tab/URL state before remounting.

Observed evidence on 2026-10-28 (Asia/Shanghai):

• Desktop: source cls; 21 filtered groups/reports; viewport/document widths both 1440.
• Narrow layout: source ""; 200 all-source reports; viewport/document widths both 375.
• Manually selecting cls again at 375px works. The collection API and persisted subscription configuration are unaffected.
• Local screenshots: F:/temp/openalice-news-stability-20261028/news-cls-desktop.png, news-cls-mobile.png, and news-cls-mobile-filtered.png.

Suspected owner: NewsPage local filter state, responsive tab remounting and URL/tab-state adoption. Root cause beyond the observed state reset has not been established.

Deferred because the current increment activates and verifies public/Chinese source intake and fixes cache eviction; it does not change the reader layout or filter lifecycle. This issue records the existing UI follow-up independently. No archived news or reading state is lost; reselecting the source is a temporary workaround.