Initial commit: Set up Garmin Health Lab project structure

- Initialize monorepo with root workspace configuration
- Set up Express.js backend with TypeScript
- Set up React 18 frontend with TypeScript
- Create database schema with SQLite
- Implement project architecture and documentation
- Add development and deployment guidelines

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

client/src/components/Layout.css

@@ -0,0 +1,129 @@
+.layout {
+  display: flex;
+  flex-direction: column;
+  min-height: 100vh;
+  background-color: #f5f5f5;
+}
+
+.header {
+  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
+  color: white;
+  padding: 2rem;
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+}
+
+.header-content {
+  max-width: 1400px;
+  margin: 0 auto;
+}
+
+.logo {
+  font-size: 1.8rem;
+  font-weight: bold;
+  margin-bottom: 0.5rem;
+}
+
+.tagline {
+  font-size: 0.9rem;
+  opacity: 0.9;
+}
+
+.container {
+  display: flex;
+  flex: 1;
+  max-width: 1400px;
+  width: 100%;
+  margin: 0 auto;
+  gap: 2rem;
+  padding: 2rem;
+}
+
+.sidebar {
+  width: 250px;
+  background: white;
+  border-radius: 8px;
+  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
+  height: fit-content;
+  position: sticky;
+  top: 2rem;
+}
+
+.nav-list {
+  list-style: none;
+  padding: 0;
+}
+
+.nav-link {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  padding: 1rem 1.5rem;
+  text-decoration: none;
+  color: #333;
+  border-left: 3px solid transparent;
+  transition: all 0.3s ease;
+}
+
+.nav-link:hover {
+  background-color: #f5f5f5;
+  border-left-color: #667eea;
+}
+
+.nav-link.active {
+  background-color: #f0f0ff;
+  border-left-color: #667eea;
+  color: #667eea;
+  font-weight: 600;
+}
+
+.icon {
+  font-size: 1.2rem;
+}
+
+.label {
+  flex: 1;
+}
+
+.content {
+  flex: 1;
+  background: white;
+  border-radius: 8px;
+  padding: 2rem;
+  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
+}
+
+.footer {
+  text-align: center;
+  padding: 2rem;
+  color: #666;
+  font-size: 0.9rem;
+  border-top: 1px solid #eee;
+}
+
+@media (max-width: 768px) {
+  .container {
+    flex-direction: column;
+    padding: 1rem;
+  }
+
+  .sidebar {
+    width: 100%;
+    position: static;
+  }
+
+  .nav-list {
+    display: flex;
+    gap: 0.5rem;
+    overflow-x: auto;
+  }
+
+  .nav-link {
+    flex: 1;
+    min-width: 100px;
+    font-size: 0.9rem;
+  }
+
+  .logo {
+    font-size: 1.4rem;
+  }
+}