feat(portal-shell): align header logo zone with the sidebar rail

Promote the sidebar's collapsed state to a shell-level
`LayoutStateService` (signal + localStorage persistence) so the header
can read it. Split the header into two zones: a logo zone whose width
matches the sidebar (16rem expanded / 4rem collapsed) and the
existing search + actions cluster on the right. The logo glyph stays
visible at both widths; the "APF Portal" wordmark hides when the
rail is collapsed.

The logo-zone right border and the sidebar right border share the
same x coordinate, so they read as one continuous column separator
running the full height of the shell. The width transition matches
the sidebar's (0.18s ease-out) and is skipped under
`prefers-reduced-motion: reduce`.

Side-effect: cleans up `<app-sidebar>` — its own signal + effect +
storage glue is gone; it now just delegates reads and the toggle
click to the service. Same UX, single source of truth, ready to
absorb future shared shell state (density, theme, ...) without
prop-drilling.

apps/portal-shell/src/app/state/layout-state.service.ts

@@ -0,0 +1,53 @@
+import { Injectable, effect, signal } from '@angular/core';
+
+/**
+ * Shell-level layout state shared by the header and the sidebar.
+ *
+ * Currently a single piece of state: whether the sidebar is collapsed
+ * to its icon-only rail. The collapsed state is persisted in
+ * `localStorage` so it survives reloads without a backend round-trip.
+ *
+ * Lives outside of `<app-sidebar>` so that `<app-header>` can also
+ * read it — that's what lets the header's logo zone size itself to
+ * match the sidebar width, and stay perfectly aligned with the rail
+ * below it. As more cross-cutting shell state lands (density, theme,
+ * panel pinning, …), it joins here rather than spreading across
+ * sibling components.
+ */
+
+const STORAGE_KEY = 'portal-shell:sidebar-collapsed';
+
+@Injectable({ providedIn: 'root' })
+export class LayoutStateService {
+  private readonly _sidebarCollapsed = signal(readPersistedCollapsed());
+
+  readonly sidebarCollapsed = this._sidebarCollapsed.asReadonly();
+
+  constructor() {
+    effect(() => {
+      const value = this._sidebarCollapsed();
+      try {
+        localStorage.setItem(STORAGE_KEY, value ? '1' : '0');
+      } catch {
+        // localStorage can throw in private-mode contexts; the UI
+        // still works, the preference just doesn't persist.
+      }
+    });
+  }
+
+  toggleSidebar(): void {
+    this._sidebarCollapsed.update((v) => !v);
+  }
+
+  setSidebarCollapsed(value: boolean): void {
+    this._sidebarCollapsed.set(value);
+  }
+}
+
+function readPersistedCollapsed(): boolean {
+  try {
+    return localStorage.getItem(STORAGE_KEY) === '1';
+  } catch {
+    return false;
+  }
+}