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/components/telegram-login/telegram-login.component.ts

@@ -1,6 +1,9 @@
-import { Component, ChangeDetectionStrategy, inject, signal, computed, effect, OnDestroy } from '@angular/core';
+import { Component, ChangeDetectionStrategy, inject, effect, OnDestroy } from '@angular/core';
 import { AuthService } from '../../services/auth.service';
 import { TranslatePipe } from '../../i18n/translate.pipe';
+import { QrLoginEngine } from '../../shared/qr-login/qr-login.engine';
+import { QrLoginAdapter } from '../../shared/qr-login/qr-login.model';
+import { AuthSession } from '../../models/auth.model';
 
 @Component({
   selector: 'app-telegram-login',
@@ -15,153 +18,39 @@ export class TelegramLoginComponent implements OnDestroy {
   showDialog = this.authService.showLoginDialog;
   status = this.authService.status;
 
-  loginUrl = signal('');
-  webSessionID = signal('');
-  qrStatus = signal<'loading' | 'ready' | 'expired' | 'error'>('loading');
-  encodedQrUrl = computed(() => encodeURIComponent(this.loginUrl()));
-  awaitingTelegramReturn = signal(false);
+  private readonly adapter: QrLoginAdapter<AuthSession> = {
+    createSession: () => this.authService.createWebSession(),
+    checkSessionOnce: webSessionID => this.authService.checkSessionOnce(webSessionID),
+    isSessionActive: session => !!session?.active,
+    getAppLoginUrl: webSessionID => this.authService.getTelegramAppLoginUrl(webSessionID),
+    onLoginComplete: () => this.authService.onTelegramLoginComplete(),
+  };
 
-  private readonly pollIntervalMs = 5000;
-  private pollTimer?: ReturnType<typeof setInterval>;
-  private readonly handleVisibilityChange = () => {
-    if (typeof document !== 'undefined' && document.visibilityState === 'visible') {
-      this.checkLoginAfterReturn();
-    }
-  };
-  private readonly handleWindowFocus = () => {
-    this.checkLoginAfterReturn();
-  };
-  private readonly handlePageShow = () => {
-    this.checkLoginAfterReturn();
-  };
+  private readonly engine = new QrLoginEngine<AuthSession>(this.adapter);
+  readonly loginUrl = this.engine.loginUrl;
+  readonly webSessionID = this.engine.webSessionID;
+  readonly qrStatus = this.engine.qrStatus;
+  readonly encodedQrUrl = this.engine.encodedQrUrl;
+  readonly awaitingTelegramReturn = this.engine.awaitingAppReturn;
 
   constructor() {
-    effect(() => {
-      if (this.showDialog()) {
-        this.initQrLogin();
-      } else {
-        this.awaitingTelegramReturn.set(false);
-        this.stopPolling();
-      }
-    });
-
-    if (typeof window !== 'undefined') {
-      document.addEventListener('visibilitychange', this.handleVisibilityChange);
-      window.addEventListener('focus', this.handleWindowFocus);
-      window.addEventListener('pageshow', this.handlePageShow);
-    }
+    effect(() => this.engine.setActive(this.showDialog()));
   }
 
   ngOnDestroy(): void {
-    this.awaitingTelegramReturn.set(false);
-    this.stopPolling();
-
-    if (typeof window !== 'undefined') {
-      document.removeEventListener('visibilitychange', this.handleVisibilityChange);
-      window.removeEventListener('focus', this.handleWindowFocus);
-      window.removeEventListener('pageshow', this.handlePageShow);
-    }
+    this.engine.destroy();
   }
 
   close(): void {
-    this.awaitingTelegramReturn.set(false);
+    this.engine.setActive(false);
     this.authService.hideLogin();
-    this.stopPolling();
   }
 
   openTelegramLogin(): void {
-    const webSessionID = this.webSessionID();
-    if (!webSessionID || typeof window === 'undefined') return;
-
-    if (!this.pollTimer) {
-      this.startPolling(webSessionID);
-    }
-
-    this.awaitingTelegramReturn.set(true);
-    window.location.href = this.authService.getTelegramAppLoginUrl(webSessionID);
+    this.engine.openAppLogin();
   }
 
   refreshQr(): void {
-    this.awaitingTelegramReturn.set(false);
-    this.stopPolling();
-    this.initQrLogin();
-  }
-
-  private initQrLogin(): void {
-    this.awaitingTelegramReturn.set(false);
-    this.qrStatus.set('loading');
-    this.loginUrl.set('');
-    this.webSessionID.set('');
-
-    this.authService.createWebSession().subscribe({
-      next: (res) => {
-        this.loginUrl.set(res.url);
-        this.webSessionID.set(res.webSessionID);
-        this.qrStatus.set('ready');
-        this.startPolling(res.webSessionID);
-      },
-      error: () => {
-        this.qrStatus.set('error');
-      }
-    });
-  }
-
-  private startPolling(webSessionID: string): void {
-    this.stopPolling();
-    if (!webSessionID) return;
-
-    let checks = 0;
-    this.pollTimer = setInterval(() => {
-      checks++;
-      if (checks > 100) {
-        this.stopPolling();
-        this.qrStatus.set('expired');
-        return;
-      }
-
-      this.authService.checkSessionOnce(webSessionID).subscribe({
-        next: (session) => {
-          if (session?.active) {
-            this.awaitingTelegramReturn.set(false);
-            this.stopPolling();
-            this.authService.onTelegramLoginComplete();
-          }
-        },
-        error: () => {
-          // Network error — keep polling
-        }
-      });
-    }, this.pollIntervalMs);
-  }
-
-  private stopPolling(): void {
-    if (this.pollTimer) {
-      clearInterval(this.pollTimer);
-      this.pollTimer = undefined;
-    }
-  }
-
-  private checkLoginAfterReturn(): void {
-    if (!this.showDialog() || !this.awaitingTelegramReturn()) {
-      return;
-    }
-
-    const webSessionID = this.webSessionID();
-    if (!webSessionID) {
-      this.awaitingTelegramReturn.set(false);
-      return;
-    }
-
-    if (!this.pollTimer) {
-      this.startPolling(webSessionID);
-    }
-
-    this.authService.checkSessionOnce(webSessionID).subscribe(session => {
-      if (session?.active) {
-        this.awaitingTelegramReturn.set(false);
-        this.stopPolling();
-        this.authService.onTelegramLoginComplete();
-      }
-    });
+    this.engine.refresh();
   }
 }