Add user authentication system with API key management (#50)

- Add User, Session, AuthSettings models with bcrypt password hashing
- Add auth endpoints: login, logout, change-password, me
- Add API key CRUD: create (orch_xxx format), list, revoke
- Add admin user management: list, create, update, reset-password
- Create default admin user on startup (admin/admin)
- Add frontend: Login page, API Keys page, Admin Users page
- Add AuthContext for session state management
- Add user menu to Layout header with login/logout/settings
- Add 15 integration tests for auth system
- Add migration 006_auth_tables.sql

frontend/src/components/Layout.tsx

@@ -1,5 +1,6 @@
-import { ReactNode } from 'react';
-import { Link, useLocation } from 'react-router-dom';
+import { ReactNode, useState, useRef, useEffect } from 'react';
+import { Link, NavLink, useLocation, useNavigate } from 'react-router-dom';
+import { useAuth } from '../contexts/AuthContext';
 import { GlobalSearch } from './GlobalSearch';
 import './Layout.css';
 
@@ -9,6 +10,31 @@ interface LayoutProps {
 
 function Layout({ children }: LayoutProps) {
   const location = useLocation();
+  const navigate = useNavigate();
+  const { user, loading, logout } = useAuth();
+  const [showUserMenu, setShowUserMenu] = useState(false);
+  const menuRef = useRef<HTMLDivElement>(null);
+
+  // Close menu when clicking outside
+  useEffect(() => {
+    function handleClickOutside(event: MouseEvent) {
+      if (menuRef.current && !menuRef.current.contains(event.target as Node)) {
+        setShowUserMenu(false);
+      }
+    }
+    document.addEventListener('mousedown', handleClickOutside);
+    return () => document.removeEventListener('mousedown', handleClickOutside);
+  }, []);
+
+  async function handleLogout() {
+    try {
+      await logout();
+      setShowUserMenu(false);
+      navigate('/');
+    } catch {
+      // Error handled in context
+    }
+  }
 
   return (
     <div className="layout">
@@ -60,6 +86,85 @@ function Layout({ children }: LayoutProps) {
               </svg>
               Docs
             </a>
+            
+            {/* User Menu */}
+            {loading ? (
+              <div className="user-menu-loading">
+                <div className="user-menu-spinner"></div>
+              </div>
+            ) : user ? (
+              <div className="user-menu" ref={menuRef}>
+                <button 
+                  className="user-menu-trigger"
+                  onClick={() => setShowUserMenu(!showUserMenu)}
+                  aria-expanded={showUserMenu}
+                  aria-haspopup="true"
+                >
+                  <div className="user-avatar">
+                    {user.username.charAt(0).toUpperCase()}
+                  </div>
+                  <span className="user-name">{user.display_name || user.username}</span>
+                  <svg width="12" height="12" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
+                    <polyline points="6 9 12 15 18 9"/>
+                  </svg>
+                </button>
+                
+                {showUserMenu && (
+                  <div className="user-menu-dropdown">
+                    <div className="user-menu-header">
+                      <span className="user-menu-username">{user.username}</span>
+                      {user.is_admin && (
+                        <span className="user-menu-badge">Admin</span>
+                      )}
+                    </div>
+                    <div className="user-menu-divider"></div>
+                    <NavLink
+                      to="/settings/api-keys"
+                      className="user-menu-item"
+                      onClick={() => setShowUserMenu(false)}
+                    >
+                      <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
+                        <path d="M21 2l-2 2m-7.61 7.61a5.5 5.5 0 1 1-7.778 7.778 5.5 5.5 0 0 1 7.777-7.777zm0 0L15.5 7.5m0 0l3 3L22 7l-3-3m-3.5 3.5L19 4"/>
+                      </svg>
+                      API Keys
+                    </NavLink>
+                    {user.is_admin && (
+                      <NavLink
+                        to="/admin/users"
+                        className="user-menu-item"
+                        onClick={() => setShowUserMenu(false)}
+                      >
+                        <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
+                          <path d="M17 21v-2a4 4 0 0 0-4-4H5a4 4 0 0 0-4 4v2"/>
+                          <circle cx="9" cy="7" r="4"/>
+                          <path d="M23 21v-2a4 4 0 0 0-3-3.87"/>
+                          <path d="M16 3.13a4 4 0 0 1 0 7.75"/>
+                        </svg>
+                        User Management
+                      </NavLink>
+                    )}
+                    <div className="user-menu-divider"></div>
+                    <button className="user-menu-item" onClick={handleLogout}>
+                      <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
+                        <path d="M9 21H5a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2h4"/>
+                        <polyline points="16 17 21 12 16 7"/>
+                        <line x1="21" y1="12" x2="9" y2="12"/>
+                      </svg>
+                      Sign out
+                    </button>
+                  </div>
+                )}
+              </div>
+            ) : (
+              <Link to="/login" className="nav-login">
+                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
+                  <path d="M15 3h4a2 2 0 0 1 2 2v14a2 2 0 0 1-2 2h-4"/>
+                  <polyline points="10 17 15 12 10 7"/>
+                  <line x1="15" y1="12" x2="3" y2="12"/>
+                </svg>
+                Login
+              </Link>
+            )}
           </nav>
         </div>
       </header>