An x in a search box clears it (#291)

Once something is typed: at the box's right end, inside it. One click
handler for every box, which clears it and fires its input event, so each
box's own handler brings its list back whole. The browser's own x, drawn
by some browsers and not others, gives way to it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/signals.ts

@@ -142,7 +142,7 @@ function signalModal(sg?: Signal){
         aria-expanded="false"></button>
         <input type="text" id="sgname" value="${esc(sg?.name||'')}" placeholder="Formula 1"></div>
       <div id="sgpicker" hidden>
-        <div class="inline"><input type="search" id="sgiconq" placeholder="Search icons: robot, car, music…" autocomplete="off">
+        <div class="inline">${searchBox('<input type="search" id="sgiconq" placeholder="Search icons: robot, car, music…" autocomplete="off">')}
           <button type="button" class="dlink" id="sgjev" title="Pick an icon for me">Auto</button>
           <button type="button" class="dlink" id="sgnoicon">Initials</button></div>
         <div class="icongrid" id="sgicons" role="listbox" aria-label="Icons"></div>