Fix MDX artifacts by renaming files to .mdx (revert config approach)

The config approach (format: 'mdx') failed because many .md files
contain angle brackets like <placeholder> that MDX interprets as JSX,
causing build failures.

Correct solution: Keep format: 'detect' and rename only files that
actually use MDX features (imports, JSX) to .mdx extension.

Files renamed to .mdx (10 total):
- src/pages/consulting (CSS module import)
- docs/database-lab/index (useBaseUrl + JSX)
- docs/joe-bot/index (useBaseUrl + JSX)
- docs/dblab-howtos/administration/install-dle-manually (Tabs)
- docs/dblab-howtos/administration/run-database-lab-on-mac (Tabs)
- docs/dblab-howtos/joe-bot/count-rows (Tabs)
- docs/dblab-howtos/joe-bot/get-database-table-index-size (Tabs)
- docs/dblab-howtos/joe-bot/query-activity-and-termination (Tabs)
- docs/dblab-howtos/joe-bot/reset-session (Tabs)
- docs/tutorials/database-lab-tutorial-amazon-rds (Tabs)

Author: claude

docs/database-lab/index.md docs/database-lab/index.mdxdocs/database-lab/index.md renamed to docs/database-lab/index.mdx

@@ -40,9 +40,10 @@ module.exports = {
   organizationName: 'postgres-ai',
   projectName: 'docs',
 
-  // Treat all .md files as MDX to support imports and JSX
+  // Use 'detect' - .md files use CommonMark, .mdx files use MDX
+  // Files needing MDX features (imports, JSX) must use .mdx extension
   markdown: {
-    format: 'mdx',
+    format: 'detect',
   },
 
   customFields: {