[fix](trx-frontend-http): improve recorder filter input and normalize file action button sizes

Widen the recordings filter input (remove max-width cap, set min-width),
add search icon placeholder, use type=search for native clear button.
Also fix download/remove button size mismatch with explicit height.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html

@@ -1147,7 +1147,7 @@
       <section class="recorder-section">
         <h3 class="recorder-section-heading">Recorded files</h3>
         <div class="recorder-filter-bar">
-          <input id="recorder-filter" type="text" class="status-input recorder-filter-input" placeholder="Filter by rig, freq, mode or date..." title="Filter recordings by filename — supports partial match (e.g. rig name, frequency, mode, date)" />
+          <input id="recorder-filter" type="search" class="status-input recorder-filter-input" placeholder="&#x1F50D; Filter recordings..." title="Filter recordings by filename — supports partial match (e.g. rig name, frequency, mode, date)" />
           <select id="recorder-sort" class="status-input recorder-sort-select">
             <option value="name-desc">Newest first</option>
             <option value="name-asc">Oldest first</option>