docs(latest): correct the browser-site comments the comix change made stale

Review findings from #98: BrowserFetcher's doc still described two sites and
two read shapes, Get's doc enumerated them a second time, and the Fallback
field doc omitted comix. The comix fixture comment now records the live
in-tab body it was re-checked against.

backend/internal/latest/sites_test.go

@@ -44,7 +44,10 @@ const challengeFixture = `<!DOCTYPE html><html><head><title>Just a moment...</ti
 //
 // Still the right fixture after comix moved behind the challenge (#98): the
 // browser read is an in-tab fetch of the Series URL, so the body a poll parses
-// is this same server-rendered HTML, not a rendered DOM.
+// is this same server-rendered HTML, not a rendered DOM. Confirmed against a
+// live cleared tab 2026-08-16 (TestSmokeComix): the in-tab fetch returned
+// 24793 bytes of server-rendered HTML that these same parses read a chapter
+// and a cover out of.
 const comixSeriesFixture = `
 {"firstChapterUrl":"/title/n8we-dungeons-and-crayons/5038739-chapter-1","latestChapterUrl":"/title/n8we-dungeons-and-crayons/11139891-chapter-80"},
 {""manga","recommended","n8we",1]":{"items":[{"latestChapterUrl":"/title/qqwrm-full-time-awakening/99999999-chapter-999"}]}