[codex] Add review app hook surfaces

[next-devin]

Summary

• Adds inert app hook slots for product rating summaries, product review widgets, review CTAs, product-card ratings, collection review feeds, homepage review feeds, and global social proof.
• Preserves native review rendering as fallback and keeps existing view_product/add_to_cart hooks in place.

Validation

• Ran git diff --check.
• No runtime tests were available for this template-only change.