fix(post-form): restore native board selector appearance

Exclude the board dropdown from post-form field chrome so it keeps the
browser default select styling, matching flag selector behavior.

src/components/post-form/__tests__/post-form.test.tsx

@@ -565,6 +565,7 @@ describe('PostForm', () => {
     expect(linkInput?.getAttribute('placeholder')).toBe('https://website.com/image.jpg');
     expect(textarea).toBeTruthy();
     expect(select).toBeTruthy();
+    expect(select?.className).toContain('boardSelector');
 
     await dispatchInput(linkInput as HTMLInputElement, 'not-a-url');
     await clickByText(table as HTMLTableElement, 'post');

src/components/post-form/post-form.module.css

@@ -69,7 +69,7 @@
   position: relative;
 }
 
-.postFormTable input[type="text"], .postFormTable textarea, .postFormTable select:not(.flagSelector) {
+.postFormTable input[type="text"], .postFormTable textarea, .postFormTable select:not(.flagSelector):not(.boardSelector) {
   border: var(--post-form-field-input-border, revert);
   font-family: var(--post-form-field-font-family, revert);
   appearance: var(--post-form-field-input-appearance, revert);
@@ -80,9 +80,13 @@
   font-size: 10pt;
 }
 
-.postFormTable input[type="text"]:focus, .postFormTable textarea:focus, .postFormTable select:not(.flagSelector):focus {
+.postFormTable input[type="text"]:focus, .postFormTable textarea:focus, .postFormTable select:not(.flagSelector):not(.boardSelector):focus {
   border: var(--post-form-field-input-focus-border, revert);
 }
+
+.boardSelector {
+  appearance: auto;
+}
       
 .postFormTable td > input[type="text"] {
   width: 244px;

src/components/post-form/post-form.tsx

@@ -432,7 +432,12 @@ const PostFormFields = ({
       <tr>
         <td>{t('board')}</td>
         <td>
-          <select aria-label={t('board')} onChange={(e) => setPublishPostOptions({ communityAddress: e.target.value })} value={communityAddress}>
+          <select
+            aria-label={t('board')}
+            className={styles.boardSelector}
+            onChange={(e) => setPublishPostOptions({ communityAddress: e.target.value })}
+            value={communityAddress}
+          >
             <option value=''>{t('choose_one')}</option>
             {isInAllView &&
               directories.map((community) =>