feat(ui): add SideDrawer component (project-local)

Right-sliding panel with portal, ESC + backdrop close, sticky header/footer,
three width sizes (md/lg/xl), transparent click-blocking backdrop, and DS token colors.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ui/src/components/SideDrawer.module.css

@@ -0,0 +1,77 @@
+.root {
+  position: fixed;
+  inset: 0;
+  z-index: 950;
+  pointer-events: none;
+}
+
+.backdrop {
+  position: absolute;
+  inset: 0;
+  pointer-events: auto;
+  /* transparent — no dim */
+}
+
+.drawer {
+  position: absolute;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  background: var(--bg-surface);
+  border-left: 1px solid var(--border);
+  box-shadow: var(--shadow-lg);
+  display: flex;
+  flex-direction: column;
+  pointer-events: auto;
+  animation: slideIn 240ms ease-out;
+}
+
+.size-md { width: 560px; max-width: 100vw; }
+.size-lg { width: 720px; max-width: 100vw; }
+.size-xl { width: 900px; max-width: 100vw; }
+
+.header {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  padding: 14px 18px;
+  border-bottom: 1px solid var(--border);
+  flex-shrink: 0;
+}
+
+.title {
+  flex: 1;
+  font-weight: 600;
+  color: var(--text-primary);
+}
+
+.closeBtn {
+  background: transparent;
+  border: 0;
+  font-size: 24px;
+  line-height: 1;
+  color: var(--text-muted);
+  cursor: pointer;
+  padding: 0 4px;
+}
+
+.closeBtn:hover { color: var(--text-primary); }
+
+.body {
+  flex: 1;
+  overflow-y: auto;
+  padding: 16px 18px;
+  color: var(--text-primary);
+}
+
+.footer {
+  flex-shrink: 0;
+  padding: 14px 18px;
+  border-top: 1px solid var(--border);
+  background: var(--bg-inset);
+}
+
+@keyframes slideIn {
+  from { transform: translateX(100%); }
+  to { transform: translateX(0); }
+}

ui/src/components/SideDrawer.test.tsx

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+import { describe, it, expect, vi } from 'vitest';
+import { render, screen, fireEvent } from '@testing-library/react';
+import { ThemeProvider } from '@cameleer/design-system';
+import type { ReactNode } from 'react';
+import { SideDrawer } from './SideDrawer';
+
+function wrap(ui: ReactNode) {
+  return render(<ThemeProvider>{ui}</ThemeProvider>);
+}
+
+describe('SideDrawer', () => {
+  it('renders nothing when closed', () => {
+    wrap(<SideDrawer open={false} onClose={() => {}} title="X">body</SideDrawer>);
+    expect(screen.queryByText('body')).toBeNull();
+  });
+
+  it('renders title, body, and close button when open', () => {
+    wrap(<SideDrawer open onClose={() => {}} title="My Title">body content</SideDrawer>);
+    expect(screen.getByText('My Title')).toBeInTheDocument();
+    expect(screen.getByText('body content')).toBeInTheDocument();
+    expect(screen.getByRole('button', { name: /close/i })).toBeInTheDocument();
+  });
+
+  it('calls onClose when close button clicked', () => {
+    const onClose = vi.fn();
+    wrap(<SideDrawer open onClose={onClose} title="X">body</SideDrawer>);
+    fireEvent.click(screen.getByRole('button', { name: /close/i }));
+    expect(onClose).toHaveBeenCalledOnce();
+  });
+
+  it('calls onClose when ESC pressed', () => {
+    const onClose = vi.fn();
+    wrap(<SideDrawer open onClose={onClose} title="X">body</SideDrawer>);
+    fireEvent.keyDown(document, { key: 'Escape' });
+    expect(onClose).toHaveBeenCalledOnce();
+  });
+
+  it('calls onClose when backdrop clicked', () => {
+    const onClose = vi.fn();
+    wrap(<SideDrawer open onClose={onClose} title="X">body</SideDrawer>);
+    fireEvent.click(screen.getByTestId('side-drawer-backdrop'));
+    expect(onClose).toHaveBeenCalledOnce();
+  });
+
+  it('renders footer when provided', () => {
+    wrap(
+      <SideDrawer open onClose={() => {}} title="X" footer={<button>Save</button>}>
+        body
+      </SideDrawer>
+    );
+    expect(screen.getByRole('button', { name: 'Save' })).toBeInTheDocument();
+  });
+});

ui/src/components/SideDrawer.tsx

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+import { useEffect, type ReactNode } from 'react';
+import { createPortal } from 'react-dom';
+import styles from './SideDrawer.module.css';
+
+interface SideDrawerProps {
+  open: boolean;
+  onClose: () => void;
+  title: ReactNode;
+  size?: 'md' | 'lg' | 'xl';
+  footer?: ReactNode;
+  children: ReactNode;
+}
+
+export function SideDrawer({
+  open, onClose, title, size = 'lg', footer, children,
+}: SideDrawerProps): React.JSX.Element | null {
+  useEffect(() => {
+    if (!open) return;
+    const handler = (e: KeyboardEvent) => { if (e.key === 'Escape') onClose(); };
+    document.addEventListener('keydown', handler);
+    return () => document.removeEventListener('keydown', handler);
+  }, [open, onClose]);
+
+  if (!open) return null;
+
+  return createPortal(
+    <div className={styles.root}>
+      <div
+        className={styles.backdrop}
+        data-testid="side-drawer-backdrop"
+        onClick={onClose}
+      />
+      <aside
+        className={`${styles.drawer} ${styles[`size-${size}`]}`}
+        role="dialog"
+        aria-modal="true"
+      >
+        <header className={styles.header}>
+          <div className={styles.title}>{title}</div>
+          <button
+            type="button"
+            aria-label="Close drawer"
+            className={styles.closeBtn}
+            onClick={onClose}
+          >
+            ×
+          </button>
+        </header>
+        <div className={styles.body}>{children}</div>
+        {footer && <footer className={styles.footer}>{footer}</footer>}
+      </aside>
+    </div>,
+    document.body
+  );
+}