fix(frontend): meet WCAG AA contrast on the config-block link text

The Storybook accessibility test flagged the share-link <code> block: with no
explicit color it inherited a muted grey that renders as #888888 on the
#f8f8f8 tertiary-fill background in CI's Chromium — a 3.33:1 contrast, below
the 4.5:1 AA threshold. Set the text to the theme's primary text token so the
colour is explicit and high-contrast in both light and dark themes instead of
depending on an inherited value that varies by browser.

frontend/src/components/clients/ConfigBlock.css

@@ -38,6 +38,7 @@ body.light .config-block .ant-tag.ant-tag-filled.ant-tag-gold {
   word-break: break-all;
   white-space: pre-wrap;
   padding: 6px 8px;
+  color: var(--ant-color-text);
   background: var(--ant-color-fill-tertiary);
   border-radius: 4px;
   user-select: all;