my-buds async add: insert new row before .applet-list-buffer, not after — keeps spacer last

`_appendBudEntry` queried `.bud-entry-buffer` (a class that doesn't exist — the
shell renders `.applet-list-buffer`), so the lookup missed and the row fell
through to appendChild, landing BELOW the trailing spacer <li> and leaving a
visible gap between the list and the new bud. Query the real class so the new
row inserts before the spacer. FT now asserts the buffer stays last-child.

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/functional_tests/test_bill_my_buds.py

@@ -79,6 +79,13 @@ class MyBudsPageTest(FunctionalTest):
 
         sel = f".bud-entry[data-bud-id='{self.alice.id}']"
         row = self.wait_for(lambda: self.browser.find_element(By.CSS_SELECTOR, sel))
+        # The trailing `.applet-list-buffer` spacer must stay LAST — the new
+        # row goes BEFORE it, not after (regression: querying the wrong buffer
+        # class dropped the row below the spacer).
+        last = self.browser.find_element(
+            By.CSS_SELECTOR, "#id_buds_list > li:last-child"
+        )
+        self.assertIn("applet-list-buffer", (last.get_attribute("class") or "").split())
         # Carries both classes (styling + tooltip-lock both key on these).
         cls = (row.get_attribute("class") or "").split()
         self.assertIn("applet-list-entry", cls)