1b50df7cd0
- the main page's form handlers move unchanged from render_page() to
handle_post(), hooked on load-{page}: inside render_page() the admin
header was already sent, so their wp_safe_redirect() calls could not work
- the setup wizard's step 4 snapshot post moves to handle_snapshot_post() on
its load hook; a failure redirects with snap_failed=1 for the notice
- Verify: unit 701, integration 577, phpcs, stan; dev36 load hook handles a
posted reset and redirects before output
- PR: PR-097