feat(web): updated tab, inline errors, card craft

Adds the Updated tab (series with an unread chapter) with its own empty
state, so "what's new" no longer means scanning the whole list.

A failed favourite/chapter/delete previously looked like an ignored tap:
htmx does not swap on a non-2xx response and nothing else said so. Errors
now surface inline on the card. The two per-card panels (chapter edit,
delete confirm) also close each other.

Mobile fixes, all measured at 360/390px rather than eyeballed:
.chapter-form and .confirm-row now wrap so the hint and the prompt take
their own row, and the number input shrinks (flex-basis 0) instead of
holding its ~20ch intrinsic width. Before this the Save button sat off
screen — 97px of page overflow at 390px, 127px at 360px — which broke
correcting a chapter number on the one device class this is built for.

Emoji glyphs replaced with inline SVG on currentColor: each rendered in a
different face at a different weight and colour, ignoring the card's own
type and colour system. No icon font or library.

Series with no scraped og:image render a title-initial monogram instead
of a blank rectangle that read as a cover still loading.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/web_test.go

@@ -483,3 +483,33 @@ func TestUIListFavouritesTab(t *testing.T) {
 		t.Fatal("favourites tab included a non-favourite")
 	}
 }
+
+func TestUIListNewTab(t *testing.T) {
+	cfg := webConfig()
+	srv, store := newWebTestServer(t, cfg)
+	seed(t, store, Bookmark{
+		Key: "asura:solo", Site: "asura", SeriesID: "solo",
+		Title: "Solo Leveling", LastChapterNum: 10,
+		LatestChapter: "Chapter 12", LatestChapterNum: floatPtr(12),
+		UpdatedAt: 2_000_000,
+	})
+	seed(t, store, Bookmark{
+		Key: "demonic:tower", Site: "demonic", SeriesID: "tower",
+		Title: "Tower of God", LastChapterNum: 5,
+		LatestChapter: "Chapter 5", LatestChapterNum: floatPtr(5),
+		UpdatedAt: 1_000_000,
+	})
+
+	rr := httptest.NewRecorder()
+	srv.ServeHTTP(rr, uiRequest(t, cfg, http.MethodGet, "/ui/list?tab=new", nil))
+	if rr.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200", rr.Code)
+	}
+	body := rr.Body.String()
+	if !strings.Contains(body, "Solo Leveling") {
+		t.Fatal("new tab omitted the series with an unread chapter")
+	}
+	if strings.Contains(body, "Tower of God") {
+		t.Fatal("new tab included a series already caught up")
+	}
+}