A feed is read up to 200 MB, not 50 (#357)

The Herd with Colin Cowherd's feed is 62 MB, its whole back catalogue, and had failed every check
since the 50 MB cap of #295 came in on 2026-10-19. The cap was there for an MP3 given as a feed;
200 MB still stops that, at four times the largest real feed seen.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/feed/src/fetch.rs

@@ -36,9 +36,10 @@ pub static FETCHES: AtomicU64 = AtomicU64::new(0);
 /// See `FETCHES`.
 pub static FETCHED_BYTES: AtomicU64 = AtomicU64::new(0);
 
-/// The most of a feed or page read. The largest feeds here are a few MB; without a limit an
-/// episode's MP3 given as a feed was read whole into memory, at every check (#295).
-pub(crate) const MAX_BODY: usize = 50 << 20;
+/// The most of a feed or page read. Without a limit an episode's MP3 given as a feed was read
+/// whole into memory, at every check (#295). Real feeds can be large: a daily show's whole back
+/// catalogue was 62 MB, and 50 MB here stopped it updating (#357).
+pub(crate) const MAX_BODY: usize = 200 << 20;
 
 /// A response's body, up to `MAX_BODY`: past it, an error, and the rest is never read.
 pub(crate) async fn read_capped(mut resp: reqwest::Response) -> Result<Vec<u8>> {