CUB-45: AgentCard final integration with sub-components

- Assemble AgentCard from AgentStatusBadge, TaskProgressBar, QuickJumpButton
- All 6 inputs functional: status, task, progress, sessionKey, channel, lastActivity
- Left-border accent matches status color (Active: #38BDF8, Idle: #2DD4BF, Thinking: #A78BFA, Error: #F87171)
- Accessibility: role="article" on card, aria-labels on all sections
- Uses tactical dark mode CSS variables from CUB-47
- Added @Input() to QuickJumpButton sessionKey for parent binding
- JumpClick output forwarded from AgentCard
- Build passes, type checking passes

frontend/src/app/components/quick-jump-button/quick-jump-button.component.ts

@@ -0,0 +1,33 @@
+import { ChangeDetectionStrategy, Component, EventEmitter, Input, Output } from '@angular/core';
+import { MatIconButton } from '@angular/material/button';
+import { MatIcon } from '@angular/material/icon';
+
+/**
+ * Quick-Jump Button — M3 FilledTonalIconButton
+ *
+ * An icon button that emits a navigation event for jumping to an agent session.
+ * Uses the Material Design 3 FilledTonalIconButton style with 8% state layer
+ * overlay on hover and focus.
+ *
+ * Per spec Section 7.3: Agent Card Component Interface
+ */
+@Component({
+  selector: 'app-quick-jump-button',
+  standalone: true,
+  imports: [MatIconButton, MatIcon],
+  templateUrl: './quick-jump-button.component.html',
+  styleUrl: './quick-jump-button.component.scss',
+  changeDetection: ChangeDetectionStrategy.OnPush,
+})
+export class QuickJumpButtonComponent {
+  /** Emitted when the button is clicked, carrying the session key for navigation. */
+  @Output() jumpClick = new EventEmitter<string>();
+
+  /** The session key to navigate to. Set by the parent agent card. */
+  @Input()
+  sessionKey = '';
+
+  onJumpClick(): void {
+    this.jumpClick.emit(this.sessionKey);
+  }
+}