refactor(portal): move the header Back registry to shared data-access

WorkspaceBackNavigationService is root-provided signal state, which the
Nx ownership contract assigns to type:data-access; type:util takes new
pure helpers and contracts only. The service and its spec move to
@iptvnator/portal/shared/data-access, and the pure WorkspaceBackTarget
contract stays in @iptvnator/portal/shared/util.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/architecture/portal-detail-navigation.md

@@ -25,12 +25,13 @@ catalog scroll positions retain the existing navigation contract below.
 
 The shell owns the page's Back action, but the workspace header renders it.
 While `backAvailable()` is true, the shell registers a target with
-`WorkspaceBackNavigationService` (`@iptvnator/portal/shared/util`): a label (the
-host's `backLabel`, else the translated "Back"), whether Escape currently runs
-it, and `run()`, which emits `backClicked`. The service keeps a stack in which
-the newest registration wins, and each release removes only its own target. A
-loading shell replaced by the loaded one therefore cannot clear its successor,
-whichever is destroyed first. The header shows the target as an `arrow_back`
+`WorkspaceBackNavigationService` (`@iptvnator/portal/shared/data-access`). The
+target, the `WorkspaceBackTarget` contract in `@iptvnator/portal/shared/util`,
+carries a label (the host's `backLabel`, else the translated "Back"), whether
+Escape currently runs it, and `run()`, which emits `backClicked`. The service
+keeps a stack in which the newest registration wins, and each release removes
+only its own target. A loading shell replaced by the loaded one therefore
+cannot clear its successor, whichever is destroyed first. The header shows the target as an `arrow_back`
 icon button in its leading slot (`data-test-id="workspace-header-back"`), to
 the right of the macOS traffic lights. That is where desktop apps and Material's
 top app bar keep navigation. The header never scrolls, so the control stays

libs/portal/downloads/feature/src/lib/offline-detail/download-offline-detail.component.spec.ts

@@ -10,10 +10,8 @@ import {
     SettingsStore,
 } from '@iptvnator/services';
 import type { DownloadMetadataSnapshot } from '@iptvnator/shared/interfaces';
-import {
-    WorkspaceBackNavigationService,
-    type WorkspaceNavigationTarget,
-} from '@iptvnator/portal/shared/util';
+import { WorkspaceBackNavigationService } from '@iptvnator/portal/shared/data-access';
+import type { WorkspaceNavigationTarget } from '@iptvnator/portal/shared/util';
 import { BehaviorSubject } from 'rxjs';
 import type {
     DownloadActionResult,

libs/portal/shared/data-access/src/index.ts

@@ -6,3 +6,5 @@ export * from './lib/live-channel-playback-queue';
 export * from './lib/source-health.service';
 
 export * from './lib/source-cleanup.service';
+
+export * from './lib/workspace-back-navigation.service';

libs/portal/shared/data-access/src/lib/workspace-back-navigation.service.spec.ts

@@ -1,9 +1,7 @@
 import { signal } from '@angular/core';
 import { TestBed } from '@angular/core/testing';
-import {
-    WorkspaceBackNavigationService,
-    WorkspaceBackTarget,
-} from './workspace-back-navigation.service';
+import { WorkspaceBackTarget } from '@iptvnator/portal/shared/util';
+import { WorkspaceBackNavigationService } from './workspace-back-navigation.service';
 
 describe('WorkspaceBackNavigationService', () => {
     function createService(): WorkspaceBackNavigationService {

libs/portal/shared/data-access/src/lib/workspace-back-navigation.service.ts

@@ -1,13 +1,5 @@
-import { computed, Injectable, Signal, signal } from '@angular/core';
-
-/** A page's Back action, rendered in the workspace header's leading slot. */
-export interface WorkspaceBackTarget {
-    /** Accessible name and tooltip; null falls back to the generic "Back". */
-    readonly label: Signal<string | null>;
-    /** True while Escape on the page runs the same action. */
-    readonly escapeShortcut: Signal<boolean>;
-    run(): void;
-}
+import { computed, Injectable, signal } from '@angular/core';
+import { WorkspaceBackTarget } from '@iptvnator/portal/shared/util';
 
 /**
  * Owns the header's Back slot. Pages register while they offer Back; the most

libs/portal/shared/util/src/index.ts

@@ -23,7 +23,7 @@ export * from './lib/category-sort-state.service';
 export * from './lib/keyboard';
 export * from './lib/keyboard-shortcuts';
 export * from './lib/remote-channel-navigation';
-export * from './lib/workspace-back-navigation.service';
+export * from './lib/workspace-back-target';
 export * from './lib/workspace-header-context.service';
 export * from './lib/workspace-view-command.types';
 export * from './lib/workspace-view-command.service';

libs/portal/shared/util/src/lib/workspace-back-target.ts

@@ -0,0 +1,10 @@
+import { Signal } from '@angular/core';
+
+/** A page's Back action, rendered in the workspace header's leading slot. */
+export interface WorkspaceBackTarget {
+    /** Accessible name and tooltip; null falls back to the generic "Back". */
+    readonly label: Signal<string | null>;
+    /** True while Escape on the page runs the same action. */
+    readonly escapeShortcut: Signal<boolean>;
+    run(): void;
+}

libs/ui/components/src/lib/portal-detail-shell/portal-detail-shell.component.spec.ts

@@ -1,7 +1,7 @@
 import { Component, signal } from '@angular/core';
 import { ComponentFixture, TestBed } from '@angular/core/testing';
 import { TranslateModule, TranslateService } from '@ngx-translate/core';
-import { WorkspaceBackNavigationService } from '@iptvnator/portal/shared/util';
+import { WorkspaceBackNavigationService } from '@iptvnator/portal/shared/data-access';
 import {
     DetailActionsTemplateDirective,
     DetailMetaTemplateDirective,

libs/ui/components/src/lib/portal-detail-shell/portal-detail-shell.component.ts

@@ -12,10 +12,8 @@ import {
     output,
     ChangeDetectionStrategy,
 } from '@angular/core';
-import {
-    WorkspaceBackNavigationService,
-    WorkspaceBackTarget,
-} from '@iptvnator/portal/shared/util';
+import { WorkspaceBackNavigationService } from '@iptvnator/portal/shared/data-access';
+import { WorkspaceBackTarget } from '@iptvnator/portal/shared/util';
 import { ContentHeroComponent } from '../content-hero/content-hero.component';
 import { ContentAboutComponent } from './content-about.component';
 import {

libs/workspace/shell/feature/src/lib/workspace-shell/services/workspace-shell.facade.ts

@@ -3,9 +3,9 @@ import { toSignal } from '@angular/core/rxjs-interop';
 import { Router } from '@angular/router';
 import { TranslateService } from '@ngx-translate/core';
 import { startWith } from 'rxjs';
+import { WorkspaceBackNavigationService } from '@iptvnator/portal/shared/data-access';
 import {
     PORTAL_EXTERNAL_PLAYBACK,
-    WorkspaceBackNavigationService,
     WorkspaceHeaderContextService,
     WorkspaceResolvedCommandItem,
 } from '@iptvnator/portal/shared/util';