Migrate blocks to apiVersion 3 for full WP 7.0 iframe support

[georgeolaru]

Context

As part of the WordPress 7.0 compatibility effort (#481), we identified that all 23 Nova Blocks blocks currently use apiVersion: 2. WordPress 7.0 introduces the iframed block editor, and apiVersion: 3 is the official way to declare full iframe compatibility.

Current state

• apiVersion 2 still works in WP 7.0 — WordPress provides a compatibility shim that wraps v2 blocks
• All critical cross-frame DOM issues have already been fixed in wave 2 of the WP7 plan (useScrollContainer, navigation block, etc.)
• The compatibility shim adds minor overhead but is not breaking

What needs to happen

1. Audit all 23 blocks for any remaining direct document/window access in their edit components
2. Fix any found issues (use ownerDocument / defaultView patterns established in wave 2)
3. Bump apiVersion from 2 to 3 in each block's block.json
4. Test each block in the iframed editor to verify no regressions

Why it was deferred

• apiVersion 2 compatibility mode works fine, so this is not blocking
• Touching 23 blocks at once carries cascading risk
• Better done as a focused effort with thorough per-block testing

Reference

• Deferral rationale: plans/2026-03-02-nova-blocks-wave5-apiversion3.md (in anima repo)
• Parent WP7 plan: plans/2026-03-02-wordpress-7-compatibility.md (in anima repo)
• Related: #481