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-api.js

@@ -0,0 +1,98 @@
+/**
+ * Auth API client module
+ * Following the pattern from static/js/watchlist.js (global exports)
+ */
+
+// Use the global API_BASE from auth-utils.js, fallback to /api
+const AUTH_API_BASE = typeof window.API_BASE !== 'undefined' ? window.API_BASE : '/api';
+
+async function login(username, password) {
+  try {
+    const response = await fetch(`${AUTH_API_BASE}/auth/login`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ username, password }),
+    });
+
+    const text = await response.text();
+    const data = window.safeJsonParse(text, {});
+
+    if (!response.ok) {
+      const errorMessage = data.detail || 'Erreur de connexion';
+      throw new Error(errorMessage);
+    }
+
+    return data;
+  } catch (error) {
+    if (error instanceof TypeError && error.message.includes('fetch')) {
+      throw new Error('Erreur de connexion au serveur');
+    }
+    throw error;
+  }
+}
+
+async function register(username, password, email = null, full_name = null) {
+  try {
+    const response = await fetch(`${AUTH_API_BASE}/auth/register`, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ username, password, email, full_name }),
+    });
+
+    const text = await response.text();
+    const data = window.safeJsonParse(text, {});
+
+    if (!response.ok) {
+      const errorMessage = data.detail || 'Erreur lors de l\'inscription';
+      throw new Error(errorMessage);
+    }
+
+    return data;
+  } catch (error) {
+    if (error instanceof TypeError && error.message.includes('fetch')) {
+      throw new Error('Erreur de connexion au serveur');
+    }
+    throw error;
+  }
+}
+
+async function logout() {
+  try {
+    const response = await fetch(`${AUTH_API_BASE}/auth/logout`, { method: 'POST' });
+    const text = await response.text();
+    const data = window.safeJsonParse(text, { status: 'success' });
+    return data;
+  } catch (error) {
+    return { status: 'success', message: 'Logged out locally' };
+  }
+}
+
+async function getMe(token) {
+  try {
+    const response = await fetch(`${AUTH_API_BASE}/auth/me`, {
+      headers: { 'Authorization': `Bearer ${token}` },
+    });
+
+    const text = await response.text();
+    const data = window.safeJsonParse(text, {});
+
+    if (!response.ok) {
+      const errorMessage = data.detail || 'Erreur de connexion';
+      throw new Error(errorMessage);
+    }
+
+    return data;
+  } catch (error) {
+    if (error instanceof TypeError && error.message.includes('fetch')) {
+      throw new Error('Erreur de connexion au serveur');
+    }
+    throw error;
+  }
+}
+
+window.authApi = {
+  login,
+  register,
+  logout,
+  getMe,
+};