Add login modal to landing page

- Show login modal when user is not authenticated
- Add handleLogin, showLoginModal, closeLoginModal functions
- Add login modal HTML with username/password form
- Add CSS styles for modal

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

public/claude-ide/projects-landing.js

@@ -27,10 +27,73 @@ async function checkAuth() {
         const data = await res.json();
 
         if (!data.authenticated) {
-            window.location.href = '/claude/login.html';
+            // Show login modal instead of redirecting
+            showLoginModal();
+            return;
+        }
+
+        // Update nav with username
+        if (data.username) {
+            document.querySelector('.nav-logo').textContent = `Claude Code (${data.username})`;
         }
     } catch (error) {
-        console.error('Auth check failed:', error);
+        console.error('[checkAuth] Error:', error);
+        showLoginModal();
+    }
+}
+
+// Show login modal
+function showLoginModal() {
+    const modal = document.getElementById('login-modal');
+    if (modal) {
+        modal.style.display = 'flex';
+    }
+}
+
+// Close login modal
+function closeLoginModal() {
+    const modal = document.getElementById('login-modal');
+    if (modal) {
+        modal.style.display = 'none';
+    }
+}
+
+// Handle login form submission
+async function handleLogin(event) {
+    event.preventDefault();
+
+    const username = document.getElementById('login-username').value;
+    const password = document.getElementById('login-password').value;
+    const errorDiv = document.getElementById('login-error');
+
+    try {
+        const res = await fetch('/claude/api/login', {
+            method: 'POST',
+            credentials: 'same-origin',
+            headers: { 'Content-Type': 'application/json' },
+            body: JSON.stringify({ username, password })
+        });
+
+        const data = await res.json();
+
+        if (data.success) {
+            // Login successful
+            closeLoginModal();
+            loadProjects();
+
+            // Update nav with username
+            if (data.username) {
+                document.querySelector('.nav-logo').textContent = `Claude Code (${data.username})`;
+            }
+        } else {
+            // Show error
+            errorDiv.textContent = data.error || 'Login failed';
+            errorDiv.style.display = 'block';
+        }
+    } catch (error) {
+        console.error('[handleLogin] Error:', error);
+        errorDiv.textContent = 'Login failed. Please try again.';
+        errorDiv.style.display = 'block';
     }
 }