fix(content): add center prop to MDX page buttons

Adds center to every <Button> in content MDX files that previously relied
on the removed .button-center global class. Also includes minor content
cleanups in the same files: eyebrow markup for section labels in
aba-therapy.mdx, and removal of extra blank lines between list items in
learner-social-club.mdx.

www/src/content/pages/en/learner-social-club.mdx

@@ -19,13 +19,9 @@ Every child needs opportunities to have fun, make friends, and build social conn
 Our integrative wellness enrichment services include:
 
 - Music
-
 - Art
-
 - Games
-
 - Dance
-
 - Recreational activities
 
 These thoughtfully designed activities help nurture your learner’s mind and body, providing holistic wellness and saving you valuable time.
@@ -35,11 +31,8 @@ These thoughtfully designed activities help nurture your learner’s mind and bo
 To ensure the best experience for your learner, please keep the following in mind:
 
 - Potty Training: Learners must be potty-trained before enrolling.
-
 - Wipes: Pack wipes for your learner. These can be stored at our clinic.
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 - Snack & Water: Send your learner with a snack and water. These items can also be stored on-site.
-
 - Pause/Cancellation Notice: Please provide AIA staff with at least a 30-day notice if you plan to pause or cancel your Learner Social Club services.
 
 ### Program Schedule & Ages Served
@@ -49,7 +42,6 @@ To ensure the best experience for your learner, please keep the following in min
 The Learner Social Club currently serves youth learners aged 8–17 years . Our flexible scheduling options currently include:
 
 - 2 days/week (Monday, Wednesday): 4:00 PM – 6:00 PM
-
 - 1 day/week (Wednesday only): 4:00 PM – 6:00 PM
 
 ### Payment Information
@@ -60,4 +52,4 @@ Interested in Trying Out Our Program?
 
 Get a 1-Day Trial Pass by emailing us at info [at] azinstitute4autism [dot] com .
 
-<Button href="https://form.jotform.com/231638510219149" target="_blank">Enroll Now</Button>
+<Button href="https://form.jotform.com/231638510219149" target="_blank" center>Enroll Now</Button>