[Docs] Document third-party app integrations for Maison

[hta218]

Context

Maison should be integration-ready for common Shopify app stacks. The docs need to explain how to connect apps safely in local and production environments.

Goal

Write Maison-specific third-party integration docs covering supported app surfaces and setup patterns.

Scope

Document setup patterns for:

• Reviews: Judge.me, Yotpo, Okendo, Loox
• Email/SMS and back-in-stock: Klaviyo, Attentive
• Subscriptions: Recharge, Skio, Appstle
• Wishlist apps
• Loyalty/referral apps
• Search/filter/merchandising apps
• Analytics/pixels

For each relevant app/category, document:

• Where the integration appears in Maison
• Which keys/tokens are needed
• Where to get those keys/tokens in the app/admin
• Which env vars/settings to use locally
• Which env vars/settings to use in production/Oxygen
• What is safe to expose to the browser vs what must stay server-only
• How to test configured and unconfigured states

Deliverables

• docs/integrations.md or equivalent
• Env var examples with placeholder values only
• Links to global Weaverse integration docs where applicable
• Troubleshooting section

Acceptance criteria

• Integration surfaces are documented.
• Local and production env setup are covered.
• Public/private token boundaries are explicit.
• No real secrets are included.
• Docs link to global Weaverse integration guides when available.

Metadata

• Theme: Maison
• Track: Theme Refresh
• Priority: High
• Milestone: July-2026