feat: add Angular frontend skeleton

frontend/src/app/pages/check-in-placeholder-page.component.ts

@@ -0,0 +1,72 @@
+import { ChangeDetectionStrategy, Component } from '@angular/core';
+import { MatCardModule } from '@angular/material/card';
+import { MatFormFieldModule } from '@angular/material/form-field';
+import { MatInputModule } from '@angular/material/input';
+
+@Component({
+  standalone: true,
+  imports: [MatCardModule, MatFormFieldModule, MatInputModule],
+  template: `
+    <section class="page">
+      <header class="page-header">
+        <p class="eyebrow">Staff check-in</p>
+        <h1>Mobile-friendly placeholder</h1>
+        <p class="supporting">
+          This route is ready for the authenticated token preview and check-in confirmation flow.
+        </p>
+      </header>
+
+      <mat-card class="content-card">
+        <mat-card-title>Future scan/lookup input</mat-card-title>
+        <mat-card-content>
+          <mat-form-field appearance="outline" class="full-width">
+            <mat-label>Opaque QR token</mat-label>
+            <input matInput placeholder="Paste or scan token" readonly>
+          </mat-form-field>
+        </mat-card-content>
+      </mat-card>
+    </section>
+  `,
+  styles: [`
+    .page {
+      max-width: 760px;
+      margin: 0 auto;
+    }
+
+    .page-header {
+      margin-bottom: 22px;
+    }
+
+    .eyebrow {
+      margin: 0 0 10px;
+      color: var(--azionelab-accent);
+      text-transform: uppercase;
+      font-size: 0.78rem;
+      font-weight: 700;
+    }
+
+    h1 {
+      margin: 0;
+      font-size: clamp(2rem, 4vw, 3rem);
+    }
+
+    .supporting {
+      color: var(--azionelab-muted);
+      line-height: 1.6;
+      max-width: 50ch;
+    }
+
+    .content-card {
+      border-radius: 8px;
+      border: 1px solid var(--azionelab-border);
+      background: var(--azionelab-surface);
+      box-shadow: var(--azionelab-shadow);
+    }
+
+    .full-width {
+      width: 100%;
+    }
+  `],
+  changeDetection: ChangeDetectionStrategy.OnPush,
+})
+export class CheckInPlaceholderPageComponent {}