SEO Next Free ultra-slim build 0.76.3

Base:
- Started from the latest working Free lab candidate 0.75.78.
- Kept the local helper UI and Free admin menu fixes.
- Continued from the strict Free build 0.75.79 and removed additional dormant
  non-Free source that is not needed for the public Free runtime.
- Continued from 0.75.82 with additional WordPress.org compatibility cleanup
  in Free diagnostics, sitemap, notifications, branding, settings, and bulk screens.
- 0.76.2 restores concrete local helper records for site verification and
  breadcrumb settings so Free users do not see generic placeholder help.
- 0.76.3 tightens the Free dashboard path, refreshes generic helper records,
  and improves editor sidebar guidance without adding Pro/Agency logic.

Physically removed advanced-only files/directories from this Free package:
- src/Modules/AIReadiness/
- src/Modules/AI/AIModule.php
- src/Modules/AI/Admin/AIAdmin.php
- src/Modules/AI/
- src/Modules/FrontendInspector/
- src/SEO/SchemaAiGenerator.php
- src/Admin/ConnectionsAdmin.php
- src/Modules/Licensing/LicensingModule.php
- src/Modules/Licensing/Admin/LicensingAdmin.php
- src/Modules/Licensing/UpdateClient.php
- src/Modules/Licensing/* except PlanMatrix.php
- src/Admin/UndoRunsAdmin.php
- src/Modules/AdminLists/
- src/Modules/ImportExport/
- src/Modules/Media/
- src/Modules/Privacy/
- src/Modules/Redirects/
- src/Modules/Revisions/Admin/
- assets/admin/ai-readiness.css
- assets/admin/autopilot.css
- assets/admin/content-clusters.css
- assets/admin/crawl-budget.css
- assets/admin/drift-monitor.css
- assets/admin/drift-monitor.js
- assets/admin/gsc.css
- assets/admin/gsc.js
- assets/admin/serp-gap.js
- assets/admin/site-crawl-bulk.js
- assets/admin/site-crawl.css
- assets/admin/task-workbench-context.js

Kept:
- Shared helper/service classes still referenced by Free admin screens.
- PlanMatrix.php, because Free Settings and module filtering use it to identify
  the Free build and avoid showing non-Free modules.
- Free-facing screens: Dashboard, Settings, SEO Notifications, Search Insights, SEO Audit, Indexation Risk, Low score pages, SEO Bulk Editor, Sitemaps, Robots, Schema Validator, URL Rules, SEO Setup Wizard.

Expectation:
- Advanced Pro/Agency pages are not shown in the Free menu.
- Direct requests to hidden Pro/Agency page slugs should be blocked.
- Free Settings forces the Simple UI surface and emits only Free-safe contextual helper records in its help JSON.
