feat(element-configs): Add TextConfig + fix Text element sizing bug

- TextConfig with 10 semantic typography variants
  * display, h1, h2, h3, h4 (headings)
  * body, body-sm (body text)
  * caption, label, code (special text)
- All variants use design tokens
- Fix Text element bug: width 'auto' instead of stretching to 100%
- Text now properly sizes to content with display: flex + width: auto

Part of STYLE-002 MVP 1 implementation.
Next: MVP 2 - Node Integration.

packages/noodl-viewer-react/src/nodes/visual/text.js

@@ -28,7 +28,9 @@ const TextNode = {
   },
   defaultCss: {
     position: 'relative',
-    display: 'flex'
+    display: 'flex',
+    // FIX: Text should size to content by default, not stretch to parent width
+    width: 'auto'
   },
   inputProps: {
     text: {