Promote the Blockscout PRO API in llms.txt (#3388)

* promoting PRO API

* add .ai to .gitignore

* add client alias to Vite configuration

* two modes for llms.txt

---------

Co-authored-by: Alexander Kolotov <alexander.kolotov@gmail.com>

Author: akolotov

.gitignore

@@ -68,3 +68,5 @@ npm-debug.log*
 /toolkit/package/dist
 license.json
 release-prs-data.json
+
+.ai