[feat](trx-wefax): implement WEFAX decoder with full server and frontend integration

Pure Rust WEFAX (Weather Facsimile) decoder supporting 60/90/120/240 LPM,
IOC 288 and 576, with automatic APT tone detection and phase alignment.

Core DSP pipeline:
- Polyphase rational resampler (48k→11025 Hz)
- FM discriminator (Hilbert FIR + instantaneous frequency)
- Goertzel tone detector (300/450/675 Hz APT tones)
- Phase alignment via cross-correlation on phasing signal
- Line slicer with linear interpolation pixel clock recovery
- Image assembler with PNG encoding

State machine: Idle→StartDetected→Phasing→Receiving→Stopping

Server integration:
- WefaxMessage/WefaxProgress in trx-core DecodedMessage
- DecoderConfig, DecoderResetSeqs, RigCommand wefax variants
- DECODER_REGISTRY entry in trx-protocol
- DecoderHistories/DecoderLoggers wefax support
- run_wefax_decoder() async task in trx-server audio.rs
- History persistence in pickledb store

Frontend integration:
- wefax.js plugin with live canvas rendering and gallery
- HTML sub-tab with canvas, gallery, toggle/clear controls
- SSE dispatch for wefax/wefax_progress events
- Decode history worker and restore support
- Toggle/clear API endpoints

19 unit tests covering resampler, FM discriminator, tone detection,
phasing, line slicing, image encoding, and decoder state machine.

https://claude.ai/code/session_019eyxgx3LuhcFZ7T5tr2Trm
Signed-off-by: Claude <noreply@anthropic.com>

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

@@ -538,6 +538,7 @@
         <button class="sub-tab" data-subtab="wspr">WSPR</button>
         <button class="sub-tab" data-subtab="rds">RDS</button>
         <button class="sub-tab" data-subtab="sat">SAT</button>
+        <button class="sub-tab" data-subtab="wefax" id="subtab-wefax">WEFAX</button>
       </div>
       <div id="subtab-overview" class="sub-tab-panel">
         <div class="plugin-item" data-decoder="ais">
@@ -600,6 +601,12 @@
             Decodes Meteor-M LRPT (137 MHz QPSK) weather satellite imagery.
           </div>
         </div>
+        <div class="plugin-item" data-decoder="wefax">
+          <strong>WEFAX Decoder</strong>
+          <div style="color:var(--text-muted); font-size:0.85rem; margin-top:0.2rem;">
+            Weather Facsimile &mdash; HF/satellite image reception (60/90/120/240 LPM)
+          </div>
+        </div>
       </div>
       <div id="subtab-rds" class="sub-tab-panel" style="display:none;">
         <div class="rds-grid">
@@ -919,6 +926,22 @@
           <small id="sat-pred-status" style="color:var(--text-muted);font-size:0.75rem;">Loading predictions&hellip;</small>
         </div>
       </div>
+      <div id="subtab-wefax" class="sub-tab-panel" style="display:none;">
+        <div class="ft8-controls">
+          <button id="wefax-decode-toggle-btn" type="button">Enable WEFAX</button>
+          <button id="wefax-clear-btn" type="button" style="margin-left:0.5rem; font-size:0.8rem;">Clear</button>
+          <small id="wefax-status" style="color:var(--text-muted);">Idle</small>
+        </div>
+        <div id="wefax-live-container" style="display:none; margin:0.5rem 0;">
+          <div style="display:flex; align-items:center; gap:0.5rem; margin-bottom:0.3rem;">
+            <strong>Receiving</strong>
+            <small id="wefax-live-info" style="color:var(--text-muted);"></small>
+          </div>
+          <canvas id="wefax-live-canvas" width="1809" height="800"
+                  style="width:100%; image-rendering:pixelated; background:#000;"></canvas>
+        </div>
+        <div id="wefax-gallery" style="display:flex; flex-wrap:wrap; gap:0.5rem;"></div>
+      </div>
     </div>
     <div id="tab-map" class="tab-panel" data-tab="map" style="display:none;">
       <template id="tmpl-map">
@@ -1476,6 +1499,7 @@
               <tr><td>CW</td><td id="about-dec-cw" class="about-status-off">Off</td></tr>
               <tr><td>APRS</td><td id="about-dec-aprs" class="about-status-off">Off</td></tr>
               <tr><td>Meteor LRPT</td><td id="about-dec-lrpt" class="about-status-off">Off</td></tr>
+              <tr id="about-dec-wefax"><td>WEFAX</td><td>Weather Facsimile decoder</td></tr>
             </table>
           </div>
           <!-- Integrations -->
@@ -1562,7 +1586,7 @@
 // Lazy plugin loader: loads plugin scripts when their tab/feature is first activated
 (function() {
   var pluginScripts = {
-    'digital-modes': ['/ft8.js', '/ft4.js', '/ft2.js', '/wspr.js', '/cw.js', '/background-decode.js', '/sat.js'],
+    'digital-modes': ['/ft8.js', '/ft4.js', '/ft2.js', '/wspr.js', '/cw.js', '/background-decode.js', '/sat.js', '/wefax.js'],
     'map': ['/map-core.js', '/leaflet-ais-tracksymbol.js', '/ais.js', '/vdes.js', '/aprs.js', '/hf-aprs.js', '/sat.js', '/sat-scheduler.js'],
     'statistics': ['/map-core.js'],
     'bookmarks': ['/bookmarks.js'],