Fix segment picker misusing removable-tag .chip/.chips styling

The new-campaign segment checkboxes reused .chip/.chips, which is
reserved codebase-wide for click-to-remove selected tags (adds a
trailing " x" and removable-tag hover styling). Give the segment
picker its own segmento-opcao/segmento-lista classes with a minimal
non-removable style instead.

public/index.html

@@ -249,7 +249,7 @@
         </div>
         <div class="field">
           <label>Segmentos</label>
-          <div id="campanha-segmentos" class="chips"></div>
+          <div id="campanha-segmentos" class="segmento-lista"></div>
         </div>
         <div class="field">
           <label>Variantes de mensagem (A/B/C)</label>