feat: add project settings page with tabbed layout

- Create SettingsTabLayout component with sidebar navigation
- Create ProjectSettingsPage with General settings tab
- Create RepositoriesSettingsTab for repo management
- Add Members placeholder tab
- Update router with settings routes
- Add CSS styles for settings layout
- Navigate to /projects/:id/settings from workspace header

apps/web/src/components/settings-tab-layout.tsx

@@ -0,0 +1,43 @@
+import React from "react";
+import { Link, useLocation } from "react-router-dom";
+
+interface Tab {
+  id: string;
+  label: string;
+  path: string;
+}
+
+interface SettingsTabLayoutProps {
+  tabs: Tab[];
+  children: React.ReactNode;
+  basePath: string;
+}
+
+export const SettingsTabLayout: React.FC<SettingsTabLayoutProps> = ({
+  tabs,
+  children,
+  basePath,
+}) => {
+  const location = useLocation();
+
+  return (
+    <div className="settings-layout">
+      <aside className="settings-sidebar">
+        <nav className="settings-nav">
+          {tabs.map((tab) => (
+            <Link
+              key={tab.id}
+              to={`${basePath}/${tab.path}`}
+              className={`settings-nav-link ${
+                location.pathname.includes(tab.path) ? "active" : ""
+              }`}
+            >
+              {tab.label}
+            </Link>
+          ))}
+        </nav>
+      </aside>
+      <main className="settings-content">{children}</main>
+    </div>
+  );
+};