[fix](trx-frontend-http): move band plan strip above waterfall in z-order

The band plan strip was visually positioned between the waterfall and
waveform areas. Move it to the top of .signal-visual-block (above the
overview/waterfall) so it renders above the waterfall. Remove the
bp-webgl transparent overrides since the strip now shows colored
segments in its own position rather than overlaying the spectrum canvas.

https://claude.ai/code/session_01KoxcohG6hn5b7kSc3mC4dA
Signed-off-by: Claude <noreply@anthropic.com>

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

@@ -107,6 +107,7 @@
     </div>
     <div id="content" style="display:none;">
     <div class="signal-visual-block">
+      <div id="spectrum-bandplan-strip" aria-label="Band plan allocations"></div>
       <div class="overview-strip">
         <canvas id="overview-canvas" aria-hidden="true"></canvas>
         <div id="rds-ps-overlay" aria-live="polite" aria-label="RDS station name"></div>
@@ -119,7 +120,6 @@
       </div>
       <div id="spectrum-panel" style="display:none;">
         <div class="spectrum-wrap">
-          <div id="spectrum-bandplan-strip" aria-label="Band plan allocations"></div>
           <div id="spectrum-bookmark-axis"></div>
           <div id="spectrum-bookmark-side-left" class="spectrum-bookmark-side spectrum-bookmark-side-left" aria-hidden="true"></div>
           <canvas id="spectrum-canvas"></canvas>