[larspohlmann]

In the magazine, a Trending story's expanded "N more sources" list now shows one full-width mini card per outlet, replacing the grid of tiny tiles. The design is mockup B from the visual round.

• Each card sits on --surface-sunken. A 104×68 picture is on the left; a source without a picture shows its favicon centred in a --surface-1 box of the same size.
• The text column holds a byline (favicon, feed, relative time), the full title (wraps, never truncated) and one line of dek.
• The thumbnail now sends no referrer and decodes asynchronously, like every other feed image in the reader.
• --mini-card-thumb-w (with a 104 / 68 aspect ratio) replaces --mini-card-thumb and --mini-card-min-w.
• Cleanup: the magazine dek mixin takes a $lines parameter, so the mini card and the compact block no longer hand-copy the one-line dek. The compact block's computed style is unchanged.

Only a story's other outlets change. A post's own duplicate copies keep their "Also in" pills (#2053).

Verified

• npm run check is green (476 suites, 6361 tests).
• Playwright trending-smoke passes in both the magazine and list layouts.
• Live on :4200: computed sizes match the mockup's values. None of the 15 stories overflows at 680px or at 375px phone width.

Closes #2055