[feat](trx-frontend-http): wire HF APRS toggle button and bookmark decoder

- Add "Enable HF APRS" toggle button to the HF APRS tab (same style as
  FT8/WSPR); button is disabled during TX like other decoder toggles
- app.js: sync button text/colour from SSE state updates
- hf-aprs.js: connect button click to /toggle_hf_aprs_decode
- bookmarks.js: add "HF APRS" checkbox to Add/Edit Bookmark decoder
  section; bmReadDecoders/bmWriteDecoders handle "hf-aprs" key; bmApply
  toggles the decoder to match bookmark preference on recall

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

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

@@ -336,6 +336,7 @@
               <div class="bm-decoder-checks">
                 <label class="bm-decoder-check"><input type="checkbox" id="bm-dec-ft8" value="ft8" /> FT8</label>
                 <label class="bm-decoder-check"><input type="checkbox" id="bm-dec-wspr" value="wspr" /> WSPR</label>
+                <label class="bm-decoder-check"><input type="checkbox" id="bm-dec-hf-aprs" value="hf-aprs" /> HF APRS</label>
               </div>
             </div>
             <label class="bm-label bm-label-wide">Comment
@@ -533,6 +534,7 @@
       </div>
       <div id="subtab-hf-aprs" class="sub-tab-panel" style="display:none;">
         <div class="ft8-controls aprs-controls">
+          <button id="hf-aprs-decode-toggle-btn" type="button">Enable HF APRS</button>
           <button id="hf-aprs-pause-btn" type="button">Pause</button>
           <button id="hf-aprs-clear-btn" type="button">Clear</button>
           <input id="hf-aprs-filter" class="ft8-filter" type="text" placeholder="Filter (e.g. SP2, beacon)" />