Phase 1 MVP: drop-in step registry + session + Markdown report

Plugin skeleton, drop-in step registry, option-backed session, single-page
checklist UI, downloadable Markdown report. Steps live as one file each
under includes/steps/ — adding/removing one is a single file change.
Step IDs are stable strings so renaming files preserves session data.

Architecture (hc-5ix.3): WPH_Steps singleton globs includes/steps/*.php,
natsort-orders by filename, requires each file (which returns a WPH_Step
instance), then applies a 'wph_steps' filter so installs can drop steps.

Session (hc-5ix.4): option-backed (per decision — plugin is installed
per-engagement, so DB-resident history would be lost on uninstall).
Single in-progress session per site; finished sessions render a report
that the user downloads/copies.

Recovery bootstrap (hc-5ix.1): detects whether wp-site-recovery is
installed + active, surfaces state on the start panel and in every
active session. Manual install for now; private update channel deferred
to hc-5ix.27.

Smoke-tested on testsite: registry discovery (13 steps in correct order),
start → update_step → progress count → finish → 8KB Markdown report →
discard cycle.

includes/steps/60-visual.php

@@ -0,0 +1,23 @@
+<?php
+if (!defined('ABSPATH')) exit;
+
+return new class extends WPH_Step {
+    public function id(): string { return 'visual'; }
+    public function title(): string { return 'Step 6 — Visual and Functional Check'; }
+    public function blurb(): string {
+        return 'Do a manual walkthrough of the site.';
+    }
+    public function sub_items(): array {
+        return [
+            'Homepage — load and visually inspect. Check for broken images, layout issues, console errors (open browser dev tools)',
+            'Navigation — click through the main menu. Confirm all links resolve correctly, no 404s on primary pages',
+            'Key pages — About, Contact, Services or equivalent. Check content renders correctly',
+            'Contact form — submit a test entry and confirm it delivers (check spam folder if no delivery). Note which form plugin is in use',
+            'If WooCommerce — check shop page loads, a product page loads, add to basket works. Do not need to complete a full test purchase every time unless flagged',
+            'If membership/login — confirm login page loads and (if test credentials available) login works',
+            'Mobile view — check the homepage and one internal page on a mobile viewport in browser dev tools',
+            'HTTPS — confirm the padlock is showing and there are no mixed content warnings',
+            'Redirects — confirm www/non-www and HTTP/HTTPS are redirecting correctly to the canonical URL',
+        ];
+    }
+};