chore: remove Supabase CLI artifacts and gitignore them

The supabase/ folder (config.toml + .gitignore) was generated by `supabase init`
and accidentally committed; it is local CLI state, not part of the suite. Remove
it and add /supabase/ to .gitignore.

Author: pyramation

.gitignore

@@ -5,3 +5,6 @@
 lerna-debug.log
 **/__tests__/**/*.js
 **/__tests__/**/*.test.d.ts
+
+# Supabase CLI local artifacts (from `supabase init`/`supabase start`)
+/supabase/