refactor: factoriser le code en plusieurs fichiers

- Extrait le CSS inline vers css/base.css, css/form.css, css/button.css
- Extrait le JS inline vers js/main.js, js/form/formHandler.js, js/storage/cvStorage.js
- index.html devient un shell qui charge les fichiers externes
- Ajoute les dossiers placeholder pour les futures sections : education, experience, hobbies

css/form.css

@@ -0,0 +1,49 @@
+.card {
+  background: #16213e;
+  border: 1px solid #2a2a4a;
+  border-radius: 12px;
+  padding: 32px;
+  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
+}
+
+.form-group {
+  margin-bottom: 20px;
+}
+
+label {
+  display: block;
+  font-size: 0.85rem;
+  color: #a0a0b0;
+  margin-bottom: 6px;
+  font-weight: 500;
+  letter-spacing: 0.03em;
+}
+
+input {
+  width: 100%;
+  padding: 11px 14px;
+  background: #1a1a2e;
+  border: 1px solid #2a2a4a;
+  border-radius: 6px;
+  color: #e0e0e0;
+  font-size: 0.95rem;
+  outline: none;
+  transition: border-color 0.2s ease, box-shadow 0.2s ease;
+}
+
+input::placeholder {
+  color: #4a4a6a;
+}
+
+input:focus {
+  border-color: #e94560;
+  box-shadow: 0 0 0 3px rgba(233, 69, 96, 0.15);
+}
+
+.success-message {
+  display: none;
+  color: #4caf50;
+  text-align: center;
+  padding-top: 16px;
+  font-size: 0.95rem;
+}