feat(project-editor): add sticky save/publish bar with validation summary

Mounts a new ProjectEditorSaveBarComponent in the editor page that shows
draft/published status, unsaved-changes indicator, and validation issues,
wiring the Task 8 facade save()/publish()/dirty/status/validationIssues
signals to an actual UI for the first time.

src/app/features/project-editor/components/save-bar/project-editor-save-bar.component.html

@@ -0,0 +1,19 @@
+<div class="project-editor-save-bar">
+  <div class="project-editor-save-bar-status">
+    <span>{{ (status() === 'published' ? 'builder.statusPublished' : 'builder.statusDraft') | translate }}</span>
+    @if (dirty()) {
+      <span class="project-editor-save-bar-dirty">{{ 'builder.unsavedChanges' | translate }}</span>
+    }
+    @if (issues().length > 0) {
+      <ul class="project-editor-save-bar-issues">
+        @for (issue of issues(); track issue.code) {
+          <li>{{ issue.message | translate }}</li>
+        }
+      </ul>
+    }
+  </div>
+  <div class="project-editor-save-bar-actions">
+    <button type="button" (click)="save()">{{ 'builder.save' | translate }}</button>
+    <button type="button" [disabled]="issues().length > 0" (click)="publish()">{{ 'builder.publish' | translate }}</button>
+  </div>
+</div>

src/app/features/project-editor/components/save-bar/project-editor-save-bar.component.scss

@@ -0,0 +1,27 @@
+.project-editor-save-bar {
+  position: sticky;
+  bottom: 0;
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-start;
+  gap: 1rem;
+  padding: 0.75rem 1rem;
+  background: var(--surface, #fff);
+  border-top: 1px solid var(--border, #ddd);
+  z-index: 5;
+}
+
+.project-editor-save-bar-dirty {
+  color: var(--warning, #b45309);
+  margin-left: 0.5rem;
+}
+
+.project-editor-save-bar-issues {
+  margin: 0.25rem 0 0;
+  padding-left: 1.25rem;
+  color: var(--danger, #b91c1c);
+}
+
+.project-editor-save-bar-actions button + button {
+  margin-left: 0.5rem;
+}

src/app/features/project-editor/components/save-bar/project-editor-save-bar.component.ts

@@ -0,0 +1,26 @@
+import { ChangeDetectionStrategy, Component, inject } from '@angular/core';
+import { TranslatePipe } from '../../../../i18n/translate.pipe';
+import { ProjectEditorFacade } from '../../facade/project-editor.facade';
+
+@Component({
+  selector: 'app-project-editor-save-bar',
+  standalone: true,
+  imports: [TranslatePipe],
+  templateUrl: './project-editor-save-bar.component.html',
+  styleUrls: ['./project-editor-save-bar.component.scss'],
+  changeDetection: ChangeDetectionStrategy.OnPush
+})
+export class ProjectEditorSaveBarComponent {
+  private readonly facade = inject(ProjectEditorFacade);
+  readonly dirty = this.facade.dirty;
+  readonly status = this.facade.status;
+  readonly issues = this.facade.validationIssues;
+
+  save(): void {
+    this.facade.save();
+  }
+
+  publish(): void {
+    this.facade.publish();
+  }
+}