fix(gitea): color ui warning/success/error/info message text, not just header

.ui.negative.message .header only tinted the header; the message body and
the warning/success/info variants had no color rule at all across every
Catppuccin theme.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

gitea/css/theme-catppuccin-frappe-rosewater.css

@@ -261,9 +261,20 @@
   color: #232634;
 }
 
-.ui.negative.message .header {
+.ui.warning.message {
+  color: var(--color-warning-text);
+}
+.ui.positive.message,
+.ui.success.message {
+  color: var(--color-success-text);
+}
+.ui.negative.message,
+.ui.error.message {
   color: var(--color-error-text);
 }
+.ui.info.message {
+  color: var(--color-info-text);
+}
 
 .ui.sha.isSigned.isVerified .shortsha {
   color: #232634;