Give the search a zero-result state, hide the strip while filtering

The client filter only toggles card.hidden, so a query matching nothing left
the list area blank while the unfiltered "Continue reading" strip stayed
populated above it — the screen contradicted itself and read as a crash.

list.html now carries a hidden no-match block; applyFilter counts visible cards,
fills the query in with textContent, and hides .recent for the duration of a
filter. The Clear-search button is handled by a delegated click listener so it
survives an htmx tab swap.

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

backend/static/filter.js

@@ -4,17 +4,43 @@
   function applyFilter() {
     var box = document.getElementById("search");
     if (!box) return;
-    var needle = box.value.trim().toLowerCase();
-    document.querySelectorAll(".card").forEach(function (card) {
+    var query = box.value.trim();
+    var needle = query.toLowerCase();
+    var cards = document.querySelectorAll(".card");
+    var visible = 0;
+    cards.forEach(function (card) {
       var title = (card.dataset.title || "").toLowerCase();
       card.hidden = needle !== "" && title.indexOf(needle) === -1;
+      if (!card.hidden) visible++;
     });
+
+    // The strip is never filtered, so leaving it up during a search puts
+    // non-matching covers above an empty list and the screen contradicts
+    // itself.
+    var recent = document.querySelector(".recent");
+    if (recent) recent.hidden = needle !== "";
+
+    // An empty bucket already explains itself server-side; this only speaks
+    // when the filter is what emptied the screen.
+    var none = document.getElementById("no-match");
+    if (none) {
+      none.hidden = !(needle !== "" && cards.length > 0 && visible === 0);
+      if (!none.hidden) none.querySelector(".no-match-q").textContent = query;
+    }
   }
 
   document.addEventListener("input", function (e) {
     if (e.target && e.target.id === "search") applyFilter();
   });
 
+  document.addEventListener("click", function (e) {
+    if (!e.target || !e.target.classList.contains("clear-search")) return;
+    var box = document.getElementById("search");
+    box.value = "";
+    applyFilter();
+    box.focus();
+  });
+
   // htmx replaces the list on a tab switch, so re-apply to the new cards.
   document.body.addEventListener("htmx:afterSwap", applyFilter);
 })();

backend/static/style.css

@@ -591,6 +591,17 @@ button { cursor: pointer; }
 }
 .empty strong { font: 400 20px var(--font-display); color: var(--paper); }
 .empty.hot strong { color: var(--ember); }
+.empty .clear-search {
+  align-self: flex-start;
+  margin-top: 4px;
+  height: 44px;
+  padding: 0 16px;
+  border: 1px solid var(--field-line);
+  background: transparent;
+  color: var(--paper-dim);
+  font: 400 16px var(--font-display);
+}
+.empty .clear-search:hover { color: var(--paper); border-color: var(--paper); }
 .empty p {
   margin: 0;
   max-width: 44ch;