Search filters for size (MB) and file extensions

- API: min_size and max_size in MB, ext as a comma-separated list. An
  extension matches as a whole word in search_text (file and entry names,
  dots as spaces), so "iso" finds .iso files but not "ISOLATION", which a
  plain search word matched as a substring. The trigram index serves it.
- Web UI: a size range and an extension field in the filter row, kept in
  the URL like the other filters.

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

public/index.html

@@ -55,6 +55,17 @@
               <option value="spot">Spotnet</option>
             </select>
           </label>
+          <span class="field-chip" title="Release size in MB">
+            <label for="min_size">Size</label>
+            <input type="number" id="min_size" min="0" step="any" inputmode="decimal" placeholder="min" aria-label="Minimum size in MB" />
+            <span aria-hidden="true">–</span>
+            <input type="number" id="max_size" min="0" step="any" inputmode="decimal" placeholder="max" aria-label="Maximum size in MB" />
+            <span class="unit">MB</span>
+          </span>
+          <span class="field-chip" title="Releases with a file or archive entry of these types, e.g. mkv, flac">
+            <label for="ext">Ext</label>
+            <input type="text" id="ext" class="ext" placeholder="mkv, flac" autocomplete="off" spellcheck="false" />
+          </span>
           <span class="chip chip-active" id="poster-filter" hidden>
             <span id="poster-filter-label"></span>
             <button type="button" id="poster-clear" aria-label="Remove poster filter">×</button>