refactor: migrate main.py to modular routers and add project roadmap

- Migrated monolithic main.py to feature-scoped routers in app/routers/
- Added GEMINI.md for project context and AI instructional guidelines
- Updated README.md with a comprehensive modernization plan (SQL migration, robust scraping DSL, frontend modernization)
- Improved authentication with cookie support and modular JS
- Updated test suite and documentation

static/js/auth-ui.js

@@ -0,0 +1,128 @@
+/**
+ * Auth UI handlers module
+ * Following the pattern from static/js/watchlist.js (global exports)
+ */
+
+async function handleLogin(event) {
+  event.preventDefault();
+  
+  const username = document.getElementById('loginUsername').value;
+  const password = document.getElementById('loginPassword').value;
+  const button = document.getElementById('loginSubmit');
+  
+  if (!button) {
+    console.error('Login button not found');
+    return;
+  }
+  
+  const originalText = button.textContent;
+  setLoading('loginSubmit', true, { loadingText: 'Connexion...', originalText });
+  
+  try {
+    const data = await window.authApi.login(username, password);
+    
+    if (data.access_token) {
+      window.setToken(data.access_token);
+      localStorage.setItem('user', JSON.stringify(data.user));
+      window.displaySuccess('authSuccess', 'Connexion réussie! Redirection...');
+      setTimeout(() => {
+        window.location.href = '/web';
+      }, 1000);
+    }
+  } catch (error) {
+    window.displayError('authError', error.message || 'Erreur lors de la connexion');
+  } finally {
+    setLoading('loginSubmit', false, { originalText });
+  }
+}
+
+async function handleRegister(event) {
+  event.preventDefault();
+  
+  const username = document.getElementById('registerUsername').value;
+  const password = document.getElementById('registerPassword').value;
+  const passwordConfirm = document.getElementById('registerPasswordConfirm').value;
+  const email = document.getElementById('registerEmail').value || null;
+  const full_name = document.getElementById('registerFullName').value || null;
+  
+  if (password !== passwordConfirm) {
+    window.displayError('authError', 'Les mots de passe ne correspondent pas');
+    return;
+  }
+  
+  const button = document.getElementById('registerSubmit');
+  if (!button) {
+    console.error('Register button not found');
+    return;
+  }
+  
+  const originalText = button.textContent;
+  setLoading('registerSubmit', true, { loadingText: 'Inscription...', originalText });
+  
+  try {
+    const data = await window.authApi.register(username, password, email, full_name);
+    
+    window.displaySuccess('authSuccess', 'Inscription réussie! Vous pouvez maintenant vous connecter.');
+    
+    setTimeout(() => {
+      window.authUi.switchTab('login');
+      document.getElementById('loginUsername').value = username;
+    }, 1500);
+  } catch (error) {
+    window.displayError('authError', error.message || 'Erreur lors de l\'inscription');
+  } finally {
+    setLoading('registerSubmit', false, { originalText });
+  }
+}
+
+function setLoading(buttonId, isLoading, options = {}) {
+  const button = document.getElementById(buttonId);
+  if (!button) {
+    return;
+  }
+
+  const defaultLoadingText = '...';
+  const loadingText = options.loadingText || defaultLoadingText;
+
+  if (isLoading) {
+    const origText = options.originalText || button.textContent;
+    button.dataset.originalText = origText;
+    button.textContent = loadingText;
+    button.disabled = true;
+  } else {
+    const origText = button.dataset.originalText || options.originalText || 'Se connecter';
+    button.textContent = origText;
+    button.disabled = false;
+  }
+}
+
+function resetLoading(buttonId, originalText) {
+  setLoading(buttonId, false, { originalText });
+}
+
+function switchTab(tab) {
+  const tabs = document.querySelectorAll('.auth-tab');
+  const forms = document.querySelectorAll('.auth-form');
+
+  tabs.forEach(t => t.classList.remove('active'));
+  forms.forEach(f => f.classList.remove('active'));
+
+  if (tab === 'login') {
+    tabs[0].classList.add('active');
+    document.getElementById('loginForm').classList.add('active');
+  } else {
+    tabs[1].classList.add('active');
+    document.getElementById('registerForm').classList.add('active');
+  }
+
+  document.getElementById('authError').classList.remove('show');
+  document.getElementById('authSuccess').classList.remove('show');
+}
+
+window.authUi = {
+  handleLogin,
+  handleRegister,
+  setLoading,
+  resetLoading,
+  switchTab,
+};