feat: Enhance demo components with new input types and layout options

- Added dropdown and radio input components to the demo for application settings.
- Introduced horizontal layout for display preferences and notification settings.
- Implemented checkbox demo with programmatic selection and clear functionality.
- Created file upload and quantity selector demos with various states and configurations.
- Added comprehensive radio input demo showcasing group behavior and various states.
- Developed text input demo with validation states and advanced features like password visibility.
- Introduced a new panel component for better content organization in demos.

ts_web/elements/dees-panel.ts

@@ -0,0 +1,77 @@
+import {
+  customElement,
+  DeesElement,
+  html,
+  css,
+  cssManager,
+  property,
+  type TemplateResult,
+} from '@design.estate/dees-element';
+import { demoFunc } from './dees-panel.demo.js';
+
+declare global {
+  interface HTMLElementTagNameMap {
+    'dees-panel': DeesPanel;
+  }
+}
+
+@customElement('dees-panel')
+export class DeesPanel extends DeesElement {
+  public static demo = demoFunc;
+
+  @property({ type: String })
+  public title: string = '';
+
+  @property({ type: String })
+  public subtitle: string = '';
+
+  public static styles = [
+    cssManager.defaultStyles,
+    css`
+      :host {
+        display: block;
+        background: ${cssManager.bdTheme('#ffffff', '#1a1a1a')};
+        border-radius: 8px;
+        padding: 24px;
+        box-shadow: 0 2px 4px ${cssManager.bdTheme('rgba(0,0,0,0.1)', 'rgba(0,0,0,0.3)')};
+        border: 1px solid ${cssManager.bdTheme('rgba(0,0,0,0.1)', 'rgba(255,255,255,0.1)')};
+      }
+
+      .title {
+        margin: 0 0 16px 0;
+        font-size: 18px;
+        font-weight: 500;
+        color: ${cssManager.bdTheme('#0069f2', '#0099ff')};
+      }
+
+      .subtitle {
+        margin: -12px 0 16px 0;
+        font-size: 14px;
+        color: ${cssManager.bdTheme('#666', '#999')};
+      }
+
+      .content {
+        color: ${cssManager.bdTheme('#333', '#ccc')};
+      }
+
+      /* Remove margins from first and last children */
+      .content ::slotted(*:first-child) {
+        margin-top: 0;
+      }
+
+      .content ::slotted(*:last-child) {
+        margin-bottom: 0;
+      }
+    `,
+  ];
+
+  public render(): TemplateResult {
+    return html`
+      ${this.title ? html`<h3 class="title">${this.title}</h3>` : ''}
+      ${this.subtitle ? html`<p class="subtitle">${this.subtitle}</p>` : ''}
+      <div class="content">
+        <slot></slot>
+      </div>
+    `;
+  }
+}