feat: extend module platform with UI slots, runtime components, CLI tooling and {{userId}} search support

Completes the generic module platform that enables modules to contribute
UI elements, runtime JS components, and search resources without any
core hardcoding.

New generic UI slot types:
- topbar.right_item: module-contributed topbar buttons
- layout.body_end_template: module-contributed dialog/overlay templates
- layout.head_style: module-contributed global CSS
- runtime.component: declarative JS component registration with phase ordering

New infrastructure:
- ModuleAutoloader: PSR-4 autoloading for module-local PHP classes
- ModuleRuntimePageBuilder: symlinks module pages into runtime directory
- ModuleRuntimeAssetPublisher: publishes module CSS/JS to web/modules/
- ModulePermissionSynchronizer: syncs module permissions to DB
- CLI scripts: module-runtime-sync, module-build, module-migrate,
  module-permissions-sync, module-assets-sync
- {{userId}} placeholder in SearchDataService for user-scoped search queries
- Component runtime with phased initialization (early/default/late)
- AppContainer.protectExistingBindings() to prevent module→core overwrites
- Architecture tests: ModuleStructureContractTest, CoreTemplateIsolationTest,
  FrontendComponentRuntimeContractTest, AppContainerIsolationContractTest

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

web/css/layout/app-page-layout.css

@@ -1,34 +1,36 @@
-.page-layout {
-  display: flex;
-  flex-direction: column;
-  min-height: 100dvh;
-}
+@layer layout {
+  .page-layout {
+    display: flex;
+    flex-direction: column;
+    min-height: 100dvh;
+  }
 
-.page-header {
-  display: flex;
-  align-items: center;
-  justify-content: space-between;
-  padding: 0.75rem 1.5rem;
-  border-bottom: 1px solid var(--border);
-}
+  .page-header {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 0.75rem 1.5rem;
+    border-bottom: 1px solid var(--app-border);
+  }
 
-.page-header .app-brand img {
-  height: 2.5rem;
-  width: auto;
-}
+  .page-header .app-brand img {
+    height: 2.5rem;
+    width: auto;
+  }
 
-.page-header nav ul {
-  display: flex;
-  gap: 1.5rem;
-  list-style: none;
-  padding: 0;
-  margin: 0;
-}
+  .page-header nav ul {
+    display: flex;
+    gap: 1.5rem;
+    list-style: none;
+    padding: 0;
+    margin: 0;
+  }
 
-.page-content {
-  flex: 1;
-  max-width: 60rem;
-  margin: 0 auto;
-  padding: 2rem 1.5rem;
-  width: 100%;
+  .page-content {
+    flex: 1;
+    max-width: 60rem;
+    margin: 0 auto;
+    padding: 2rem 1.5rem;
+    width: 100%;
+  }
 }