fix(electrobun): replace native <select> with fully themed custom dropdowns

All 3 wizard selects (branch, group, shell) now use custom dropdown
components with --ctp-* themed menu, hover states, active highlight.
No native OS styling leaks through.

ui-electrobun/src/mainview/ProjectWizard.svelte

@@ -59,6 +59,12 @@
   let shellChoice = $state('bash');
 
   const SHELLS = ['bash', 'zsh', 'fish', 'sh'];
+  let branchDDOpen = $state(false);
+  let groupDDOpen = $state(false);
+  let shellDDOpen = $state(false);
+  let branchLabel = $derived(selectedBranch || 'main');
+  let groupLabel = $derived(groups.find(g => g.id === selectedGroupId)?.name ?? 'Select');
+  function closeAllDD() { branchDDOpen = false; groupDDOpen = false; shellDDOpen = false; }
   const EMOJI_GRID = ['📁', '🚀', '⚡', '🔧', '🌐', '📦', '🎯', '💡', '🔬', '🎨', '📊', '🛡️', '🤖', '🧪', '🏗️', '📝'];
 
   // ── Step 3: Agent ──────────────────────────────────────────
@@ -373,11 +379,17 @@
 
       {#if isGitRepo && branches.length > 0}
         <label class="wz-label">{t('wizard.step2.branch' as any)}</label>
-        <select class="wz-select" bind:value={selectedBranch}>
-          {#each branches as br}
-            <option value={br}>{br}</option>
-          {/each}
-        </select>
+        <div class="wz-dd" style="position:relative;">
+          <button class="wz-dd-btn" onclick={() => { closeAllDD(); branchDDOpen = !branchDDOpen; }}>
+            <span>{branchLabel}</span><span class="wz-dd-chev">▾</span>
+          </button>
+          <div class="wz-dd-menu" style:display={branchDDOpen ? 'block' : 'none'}>
+            {#each branches as br}
+              <button class="wz-dd-item" class:active={selectedBranch === br}
+                onclick={() => { selectedBranch = br; branchDDOpen = false; }}>{br}</button>
+            {/each}
+          </div>
+        </div>
 
         <label class="wz-toggle-row">
           <input type="checkbox" bind:checked={useWorktrees} />
@@ -386,11 +398,17 @@
       {/if}
 
       <label class="wz-label">{t('wizard.step2.group' as any)}</label>
-      <select class="wz-select" bind:value={selectedGroupId}>
-        {#each groups as g}
-          <option value={g.id}>{g.name}</option>
-        {/each}
-      </select>
+      <div class="wz-dd" style="position:relative;">
+        <button class="wz-dd-btn" onclick={() => { closeAllDD(); groupDDOpen = !groupDDOpen; }}>
+          <span>{groupLabel}</span><span class="wz-dd-chev">▾</span>
+        </button>
+        <div class="wz-dd-menu" style:display={groupDDOpen ? 'block' : 'none'}>
+          {#each groups as g}
+            <button class="wz-dd-item" class:active={selectedGroupId === g.id}
+              onclick={() => { selectedGroupId = g.id; groupDDOpen = false; }}>{g.name}</button>
+          {/each}
+        </div>
+      </div>
 
       <label class="wz-label">{t('wizard.step2.icon' as any)}</label>
       <div class="wz-emoji-grid">
@@ -401,11 +419,17 @@
       </div>
 
       <label class="wz-label">{t('wizard.step2.shell' as any)}</label>
-      <select class="wz-select" bind:value={shellChoice}>
-        {#each SHELLS as sh}
-          <option value={sh}>{sh}</option>
-        {/each}
-      </select>
+      <div class="wz-dd" style="position:relative;">
+        <button class="wz-dd-btn" onclick={() => { closeAllDD(); shellDDOpen = !shellDDOpen; }}>
+          <span>{shellChoice}</span><span class="wz-dd-chev">▾</span>
+        </button>
+        <div class="wz-dd-menu" style:display={shellDDOpen ? 'block' : 'none'}>
+          {#each SHELLS as sh}
+            <button class="wz-dd-item" class:active={shellChoice === sh}
+              onclick={() => { shellChoice = sh; shellDDOpen = false; }}>{sh}</button>
+          {/each}
+        </div>
+      </div>
 
       <div class="wz-footer">
         <button class="wz-btn secondary" onclick={goBack}>{t('wizard.back' as any)}</button>
@@ -521,19 +545,31 @@
   .wz-input:focus, .wz-select:focus, .wz-textarea:focus { outline: none; border-color: var(--ctp-blue); }
   .wz-input::placeholder, .wz-textarea::placeholder { color: var(--ctp-overlay0); }
   .wz-textarea { resize: vertical; min-height: 3rem; }
-  .wz-select {
-    cursor: pointer;
-    -webkit-appearance: none;
-    appearance: none;
-    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%23a6adc8' stroke-width='2'%3E%3Cpolyline points='6 9 12 15 18 9'/%3E%3C/svg%3E");
-    background-repeat: no-repeat;
-    background-position: right 0.5rem center;
-    padding-right: 1.75rem;
+  /* Custom themed dropdown */
+  .wz-dd { width: 100%; }
+  .wz-dd-btn {
+    width: 100%; display: flex; align-items: center; justify-content: space-between;
+    padding: 0.375rem 0.5rem; background: var(--ctp-surface0);
+    border: 1px solid var(--ctp-surface1); border-radius: 0.25rem;
+    color: var(--ctp-text); font-size: 0.8125rem; font-family: var(--ui-font-family);
+    cursor: pointer; text-align: left;
   }
-  .wz-select option {
-    background: var(--ctp-surface0);
-    color: var(--ctp-text);
+  .wz-dd-btn:hover { border-color: var(--ctp-surface2); }
+  .wz-dd-chev { color: var(--ctp-overlay1); font-size: 0.75rem; }
+  .wz-dd-menu {
+    position: absolute; top: 100%; left: 0; right: 0; z-index: 20;
+    background: var(--ctp-mantle); border: 1px solid var(--ctp-surface1);
+    border-radius: 0.25rem; margin-top: 0.125rem;
+    max-height: 10rem; overflow-y: auto;
+    box-shadow: 0 0.25rem 0.75rem color-mix(in srgb, var(--ctp-crust) 50%, transparent);
   }
+  .wz-dd-item {
+    width: 100%; padding: 0.3125rem 0.5rem; background: none; border: none;
+    color: var(--ctp-text); font-size: 0.8125rem; font-family: var(--ui-font-family);
+    cursor: pointer; text-align: left;
+  }
+  .wz-dd-item:hover { background: var(--ctp-surface0); }
+  .wz-dd-item.active { color: var(--ctp-blue); background: color-mix(in srgb, var(--ctp-blue) 10%, transparent); }
 
   /* Themed checkboxes */
   input[type="checkbox"] {