feat(sprint18): editor autosave/reset, admin auth, QR reuse, Ed25519 prep

- Project editor: persist draft to localStorage, restore on reload,
  last-saved/draft-restored status indicators, section/whole-draft reset
  with confirmation.
- Extract shared QR/polling/expiry engine from TelegramLoginComponent
  (shared/qr-login) and reuse it for a new admin login flow.
- Admin authentication kept fully separate from customer session:
  own cookie/localStorage keys, signals, guard, and header interceptor
  (core/admin-auth).
- ?login=true / ?adminLogin=true open the respective login dialog for
  manual testing.
- Ed25519 challenge/verify interfaces (fail-closed no-op binding) ready
  for backend delivery.
- Document autosave/reset/admin-auth/QR-reuse/Ed25519 model and the
  remaining full-field-coverage gap in docs/Project-Editor.md.

src/app/features/project-editor/services/project-editor-draft-storage.service.ts

@@ -0,0 +1,51 @@
+import { Injectable } from '@angular/core';
+import { BootstrapConfig } from '../../../shared/models/config';
+
+const DRAFT_STORAGE_KEY = 'projectEditor.draftBootstrap.v1';
+const DRAFT_SAVED_AT_KEY = 'projectEditor.draftSavedAt.v1';
+
+interface StoredDraft {
+  tenantId: string;
+  bootstrap: BootstrapConfig;
+  savedAt: number;
+}
+
+@Injectable({ providedIn: 'root' })
+export class ProjectEditorDraftStorageService {
+  save(bootstrap: BootstrapConfig): number {
+    const savedAt = Date.now();
+    const payload: StoredDraft = { tenantId: bootstrap.tenant.id, bootstrap, savedAt };
+    try {
+      localStorage.setItem(DRAFT_STORAGE_KEY, JSON.stringify(payload));
+      localStorage.setItem(DRAFT_SAVED_AT_KEY, String(savedAt));
+    } catch {
+      // storage unavailable (private mode / quota) - draft simply won't persist
+    }
+    return savedAt;
+  }
+
+  load(tenantId: string): { bootstrap: BootstrapConfig; savedAt: number } | null {
+    try {
+      const raw = localStorage.getItem(DRAFT_STORAGE_KEY);
+      if (!raw) {
+        return null;
+      }
+      const parsed = JSON.parse(raw) as StoredDraft;
+      if (parsed.tenantId !== tenantId) {
+        return null;
+      }
+      return { bootstrap: parsed.bootstrap, savedAt: parsed.savedAt };
+    } catch {
+      return null;
+    }
+  }
+
+  clear(): void {
+    try {
+      localStorage.removeItem(DRAFT_STORAGE_KEY);
+      localStorage.removeItem(DRAFT_SAVED_AT_KEY);
+    } catch {
+      // ignore
+    }
+  }
+}