Add a settings page for profit display and default stack

- Per-device toggle to hide your own net and the net ranking at tables
- Default starting stack set in settings; creating a table saves the
  stack, SB and BB used as the next defaults
- Number fields on create and settings select all on focus

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

public/create.html

@@ -88,7 +88,7 @@
         <div class="list">
           <div class="cell field-cell value-right">
             <label for="stack">開始スタック</label>
-            <input id="stack" type="number" inputmode="numeric" min="10" step="1" value="1000">
+            <input id="stack" type="number" inputmode="numeric" min="10" step="1">
           </div>
           <div class="cell field-cell value-right">
             <label for="sb">スモールブラインド</label>