Admin pages: manifest admin_pages[] slot + lazy import + capability-gated routing

[tayebmokni]

Summary

Implement the admin pages slot: the manifests admin_pages array is the single canonical mechanism for plugin-supplied admin pages. The admin shell composes its menu from this array, gates access by the entrys capability field, and lazy-imports the entry ES module when the route is visited.

The SDKs registerMenu/registerAdminRoute calls are sugar that writes into this slot at build time, not a parallel runtime registry. Backward-compat: validator accepts legacy web.admin.menu shape and rewrites it.

Design reference

• docs/02-plugin-system.md §7.3 (cross-refs doc 05)

Acceptance criteria

• At plugin Activate, host parses manifest.admin_pages[] and registers each entry in the admin shells page registry: {slug, parent, title, icon, capability, entry, plugin_slug, plugin_version}
• Admin shell menu composition (lives in admin app — see doc 05) reads from this registry to build the sidebar
• Route resolution: when admin visits /admin/{plugin_slug}/{page_slug} the hosts admin router serves the layout shell and the pages entry ES module is lazy-imported via the import map
• Client-side 403: if current user lacks the capability, the admin shell shows a 403 without importing the entry
• Server-side enforcement: plugin REST endpoints serving the pages data INDEPENDENTLY re-check the capability (defense in depth)
• Parent nesting: parent: "tools" nests under the core "Tools" menu; parent: "{slug}/{page-slug}" nests under another plugin page
• Backward-compat: manifest validator accepts legacy web.admin.menu shape and rewrites to admin_pages at install time; emits a deprecation warning to the plugin author
• Tests: page registered/unregistered across activate/deactivate; capability gate enforced; legacy web.admin.menu rewrite preserves semantics

Dependencies

#45 (lifecycle), #214 (frontend SDK), doc 05 (admin shell)

Complexity

M

[tayebmokni]

Closing — shipped in the final-wave PR (#487-#492). Auto-close only fires for first ref.