ui: competition logos are pixelated - most are scraped favicons stretched into a banner

[yakew7]

Problem

public/competitions/*.png (added in b39cc89, "logo banners on competition grid cards") has 100 logo files, but most are far too small for how they're actually displayed:

40 files are 32x32
19 files are 16x16
11 files are 48x48

That's 70 of 100 logos at favicon resolution. competition-card.tsx's grid variant renders them at aspect-[2/1] (a banner spanning the full card width, easily 300px+ wide) via next/image fill, so a 16x16 or 32x32 source gets stretched roughly 10-20x past its native resolution. That's the pixelation.

Likely cause

These look like they were pulled from a favicon service (e.g. Google's s2/favicons endpoint, or each site's own favicon.ico/small touch-icon) rather than each organizer's actual logo mark. A handful of files (coca-cola-scholars.png at 360x360, a couple of others in the 100-256px range) look like real logos and render fine at this size — the fix is to bring the other ~70 up to that same bar, not to redo the ones that already work.

Fix

For each competition whose logo is under ~128px:

1. Find the organizer's actual logo (their site's header/press-kit, or a larger touch-icon like apple-touch-icon.png which is usually 180x180+, not the tiny favicon.ico)
2. Replace the file at public/competitions/<id>.png, matching the existing filename-to-id convention
3. Keep it reasonably sized (a few hundred px on the long edge is enough for a card banner — no need for multi-MB source files)

There's no committed script that generated these, so there's nothing to fix upstream - it's a per-file replacement job. If you do write a fetch script while you're in there, commit it under scripts/ so this doesn't have to be a manual one-off again next time new competitions get logos.

Acceptance criteria

• No competition logo in public/competitions/ is under ~128px on its long edge
• Grid-view competition cards no longer show visibly pixelated/blurry logos