Polish answer notifications and editing controls.

Brand notification emails, log accepted sends, and keep answer editing collapsed until explicitly opened.

static/app.css

@@ -610,6 +610,44 @@ input:focus, textarea:focus, .btn:focus-visible, .chip:focus-visible, .vote-btn:
   font-size: 0.72rem;
 }
 
+.answer-editor {
+  margin-top: 16px;
+  border-top: 1px solid var(--line);
+}
+
+.answer-editor summary {
+  display: flex;
+  width: fit-content;
+  min-height: 44px;
+  align-items: center;
+  color: var(--muted);
+  font-family: var(--mono);
+  font-size: 0.72rem;
+  letter-spacing: 0.06em;
+  text-transform: uppercase;
+  text-decoration: underline;
+  cursor: pointer;
+  list-style: none;
+}
+
+.answer-editor summary::-webkit-details-marker { display: none; }
+.answer-editor summary:hover,
+.answer-editor[open] summary { color: var(--signal); }
+.answer-editor summary:focus-visible {
+  outline: 2px solid var(--signal);
+  outline-offset: 2px;
+}
+
+.answer-editor .answer-form { margin-top: 4px; }
+
+.answer-form-actions {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 8px;
+}
+
+.answer-form-actions .btn { flex: 1 1 10rem; }
+
 .waiting { color: var(--muted); margin: 0; font-family: var(--mono); font-size: 0.8rem; }
 
 .auth-wrap {