feat(ebook): improve search UX with grid actions and Enter-to-submit

Add a two-column grid layout for the admin protected-phrases actions
and submit the search form on Enter (Shift+Enter for newline).

python/ebook_search/api/templates/search.html

@@ -7,7 +7,8 @@
     <h1>Search</h1>
     <form class="card" hx-post="/search" hx-target="#results" hx-swap="innerHTML">
         <label for="query">What are you looking for?</label>
-        <textarea id="query" name="query" rows="4" placeholder="Ask a question or paste a passage…" required></textarea>
+        <textarea id="query" name="query" rows="4" placeholder="Ask a question or paste a passage…" required
+            onkeydown="if (event.key === 'Enter' && !event.shiftKey) { event.preventDefault(); this.form.requestSubmit(); }"></textarea>
         <div class="form-row">
             <div class="search-toggles">
                 <label class="check">