Unscope lnw chapter scan, truncate at comment thread (#87)

The Poll scoped the lightnovelworld scan to the slug derived from the
stored address, so a Series publishing chapters under more than one
Chapter Slug froze its Latest Chapter. The branch now matches any
chapter-shaped address on the host (lnwChapterRe) and scans only the
body before the wpdiscuz thread marker (wpd-threads); a body without
the marker is skipped and logged with its length, never scanned whole.
The size-cap comment now states the measured ~3.5x headroom.

backend/internal/latest/sites_test.go

@@ -1,6 +1,9 @@
 package latest
 
-import "testing"
+import (
+	"strings"
+	"testing"
+)
 
 // Trimmed from https://asurascans.com/comics/chronicles-of-the-demon-faction-f886a8af
 // fetched 2026-07-26. The first anchor is the "First Chapter" shortcut: it is a
@@ -408,19 +411,33 @@ func TestLatestChapterFrom(t *testing.T) {
 			body:      novelfullSeriesFixture,
 			wantOK:    false,
 		},
+		// Stored before the slug split, so the address carries the ...-not
+		// Chapter Slug; the 100-423 block under the other slug must still win.
+		// The body is the chapter-list portion of lnwSeriesFixture with the
+		// comment block omitted (that is the next case's job); the marker is
+		// kept, because a body without it is skipped, not scanned.
 		{
-			name:      "lightnovelworld takes the max on a split-slug novel",
+			name:      "lightnovelworld max spans both chapter slugs",
+			site:      "lightnovelworld",
+			seriesURL: "https://lightnovelworld.net/novel/all-jobs-and-classes-i-just-wanted-one-skill-not/",
+			body:      strings.SplitN(lnwSeriesFixture, lnwCommentMarker, 2)[0] + lnwCommentMarker,
+			wantOK:    true, wantNum: 423, wantLabel: "Chapter 423",
+		},
+		{
+			name:      "lightnovelworld comment anchor cannot set the latest chapter",
 			site:      "lightnovelworld",
 			seriesURL: "https://lightnovelworld.net/novel/all-jobs-and-classes-i-just-wanted-one-skill-not-them-all/",
 			body:      lnwSeriesFixture,
 			wantOK:    true, wantNum: 423, wantLabel: "Chapter 423",
 		},
+		// Marker removed from the fixture, comment block still present: a
+		// redesign must degrade into a skip, never into the comment's number.
 		{
-			name:      "lightnovelworld tolerates a series url with no trailing slash",
+			name:      "lightnovelworld body without the comment marker is skipped",
 			site:      "lightnovelworld",
-			seriesURL: "https://lightnovelworld.net/novel/all-jobs-and-classes-i-just-wanted-one-skill-not-them-all",
-			body:      lnwSeriesFixture,
-			wantOK:    true, wantNum: 423, wantLabel: "Chapter 423",
+			seriesURL: "https://lightnovelworld.net/novel/all-jobs-and-classes-i-just-wanted-one-skill-not-them-all/",
+			body:      strings.ReplaceAll(lnwSeriesFixture, lnwCommentMarker, ""),
+			wantOK:    false,
 		},
 		{
 			name:      "lightnovelworld yields nothing on a challenge page",