Harden paywall detection + render paywalled stamp on cards

Bypass-UA retry (Googlebot + Google referer) for soft paywalls, JSON-LD
gating scoped to Article-typed nodes, HTTP 402 treated as explicit
paywall, Wayback freshness filter (30d cap), archive.today as secondary
archive fallback, and transport failures no longer trigger snapshot
swaps. When gating is detected and no archive workaround succeeds, the
story is stored with paywalled=1 and the web card renders a diagonal
red rubber-stamp overlay so readers know the link is gated.

internal/web/handlers.go

@@ -22,6 +22,7 @@ type StoryView struct {
 	Source     string
 	SeenAt     time.Time
 	Posted     bool
+	Paywalled  bool   // source is gated and no archive workaround succeeded
 	Channel    string // channel slug; also the theme key
 }
 
@@ -34,6 +35,7 @@ func toView(s storage.Story) StoryView {
 		Source:     s.Source,
 		SeenAt:     time.Unix(s.SeenAt, 0),
 		Posted:     s.Posted,
+		Paywalled:  s.Paywalled,
 		Channel:    s.Channel,
 	}
 }

internal/web/static/css/input.css

@@ -92,4 +92,36 @@ html[data-phase="night"] {
     -webkit-box-orient: vertical;
     overflow: hidden;
   }
+
+  /* "PAYWALLED" diagonal rubber stamp overlay — slapped across the whole
+     card when the source is gated and no archive snapshot worked. The card
+     stays clickable (link still goes to the original); the stamp is just
+     visual warning. pointer-events:none keeps it from eating clicks. */
+  .paywall-stamp {
+    position: absolute;
+    inset: 0;
+    pointer-events: none;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    z-index: 5;
+    background: rgba(255, 250, 240, 0.18);
+  }
+  .paywall-stamp::before {
+    content: "PAYWALLED";
+    font-family: var(--font-display, ui-sans-serif), system-ui, sans-serif;
+    font-weight: 900;
+    font-size: clamp(1rem, 3.2vw, 1.75rem);
+    letter-spacing: 0.12em;
+    color: rgba(180, 30, 30, 0.85);
+    border: 0.28rem double rgba(180, 30, 30, 0.85);
+    padding: 0.3rem 0.9rem;
+    transform: rotate(-15deg);
+    text-shadow: 0 1px 0 rgba(255,255,255,0.4);
+    box-shadow: inset 0 0 0 2px rgba(255,255,255,0.15);
+    background: rgba(255, 240, 230, 0.55);
+    border-radius: 0.25rem;
+    /* slight roughness to mimic a real ink stamp */
+    filter: contrast(1.05);
+  }
 }

internal/web/templates/_card.html

@@ -1,6 +1,6 @@
 {{define "card"}}
 <a href="{{.Story.ArticleURL}}" target="_blank" rel="noopener noreferrer"
-   class="group block rounded-3xl bg-[color:var(--card)] border-2 {{if .Story.Posted}}border-theme-{{.Theme}} glow-theme-{{.Theme}}{{else}}border-[color:var(--ink)]/10{{end}} shadow-pete overflow-hidden hover:-translate-y-1 hover:shadow-pete-lg transition">
+   class="group relative block rounded-3xl bg-[color:var(--card)] border-2 {{if .Story.Posted}}border-theme-{{.Theme}} glow-theme-{{.Theme}}{{else}}border-[color:var(--ink)]/10{{end}} shadow-pete overflow-hidden hover:-translate-y-1 hover:shadow-pete-lg transition">
   {{if .Story.ImageURL}}
   <div class="aspect-[16/10] w-full overflow-hidden bg-[color:var(--ink)]/5">
     <img src="{{thumb .Story.ImageURL}}" alt="" loading="lazy" decoding="async"
@@ -28,5 +28,8 @@
     <p class="text-sm text-[color:var(--ink)]/70 line-clamp-3">{{.Story.Lede}}</p>
     {{end}}
   </div>
+  {{if .Story.Paywalled}}
+  <div class="paywall-stamp" aria-label="Paywalled article"></div>
+  {{end}}
 </a>
 {{end}}