feat: module architecture improvements — session keys, dependency graph, event dispatcher, deactivation hooks

Six targeted improvements to the modular monolith platform:

1. Fix AddressBook session key prefix to follow module.<id>.* convention
2. Move ADDRESS_BOOK_VIEW permission constant from core PermissionService into module
3. Add declarative JSON schema for module manifests (.agents/contracts/)
4. Add `requires` field with missing-dependency and circular-dependency detection
5. Add lightweight fire-and-forget event dispatcher (user.created/deleted/login/logout)
6. Add module deactivation hook interface and CLI script (bin/module-deactivate.php)

Includes 15 new architecture/unit tests covering all new functionality.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/Service/Access/PermissionService.php

@@ -42,7 +42,6 @@ class PermissionService
     public const USERS_ACCESS_PDF = 'users.access_pdf';
     public const USERS_SELF_UPDATE = 'users.self_update';
     public const USERS_UPDATE_ASSIGNMENTS = 'users.update_assignments';
-    public const ADDRESS_BOOK_VIEW = 'address_book.view';
     public const TENANTS_VIEW = 'tenants.view';
     public const TENANTS_CREATE = 'tenants.create';
     public const TENANTS_UPDATE = 'tenants.update';