Signals: an admin chooses whether the server's TypeSafe key pays for everyone (#271)

With signals_on_server set and TYPESAFE_KEY present, the judge asks Jev
about everyone's Signals on the server's key; otherwise each person turns
Signals on in Settings with a key of their own, which is now checked with
TypeSafe before it is saved. The Signals folder shows only when they are on.

The browser suite's daemon inherited the shell's TYPESAFE_KEY, so fixture
feeds were sent to the real TypeSafe to be categorised; it is blanked now,
and an empty key counts as none.

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

web/src/admin.ts

@@ -53,6 +53,11 @@ async function drawServer(){
       <input type="number" id="gart" min="0" value="${g.art_cache_mb}">
       <span class="hint">Show and episode artwork is kept here once shown, so it loads from iPX
       instead of each publisher. Over this, what has gone longest unshown is dropped first.</span></div>
+    <div class="field"><label class="check"><input type="checkbox" id="gsig"${g.signals_on_server ? ' checked' : ''}${g.typesafe_server_key ? '' : ' disabled'}>
+      Signals for everyone, on this server's TypeSafe key</label>
+      <span class="hint">${g.typesafe_server_key
+        ? 'On, everyone has Signals and every item read for one is a call on this server\'s key. Off, each person turns Signals on in their own Settings with a key of their own.'
+        : 'This server has no TypeSafe key (<code>TYPESAFE_KEY</code>), so each person uses their own.'}</span></div>
     <div class="field"><label>Download folder</label>
       <span class="hint" style="overflow-wrap:anywhere">${esc(g.download_dir)}</span></div>
     <div class="cardacts"><button class="btn primary" id="gsave">${ICON.check} Save</button></div>`;
@@ -64,7 +69,9 @@ async function drawServer(){
         media_types: $<HTMLInputElement>('#gtypes').value.split(',').map((t: string) => t.trim()).filter(Boolean),
         max_total_gb: Number($<HTMLInputElement>('#gquota').value) || 0,
         max_age_days: Number($<HTMLInputElement>('#gage').value) || 0,
-        art_cache_mb: Math.max(0, Number($<HTMLInputElement>('#gart').value) || 0)})});
+        art_cache_mb: Math.max(0, Number($<HTMLInputElement>('#gart').value) || 0),
+        // Left alone while the server has no key to offer, rather than switched off.
+        ...($<HTMLInputElement>('#gsig').disabled ? {} : {signals_on_server: $<HTMLInputElement>('#gsig').checked})})});
       toast('Settings saved');
     }catch(e){ toast(why(e), true); }
   };