fix(forms): erreurs de validation par champ au blur

- Erreurs affichées sous chaque champ obligatoire (fr-error-text DSFR)
  au lieu d'un message global en haut du formulaire
- Déclenchement sur blur (sortie du champ) et effacement sur input
- Concerne la modale édition API et la modale catégorie

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

front-public/src/app/pages/api-detail/api-detail.component.ts

@@ -242,13 +242,19 @@ import { ApiEntry, Category } from '@datacat/shared';
             @if (editError()) {
               <div class="fr-alert fr-alert--error fr-mb-2w"><p>{{ editError() }}</p></div>
             }
-            <div class="fr-input-group fr-mb-2w">
+            <div class="fr-input-group fr-mb-2w" [class.fr-input-group--error]="editTitleError()">
               <label class="fr-label" for="edit-title">Titre <span style="color:var(--text-default-error)">*</span></label>
-              <input id="edit-title" class="fr-input" type="text" [value]="editTitle()" (input)="editTitle.set($any($event.target).value)" />
+              <input id="edit-title" class="fr-input" [class.fr-input--error]="editTitleError()" type="text" [value]="editTitle()"
+                     (input)="editTitle.set($any($event.target).value); editTitleError.set(false)"
+                     (blur)="editTitleError.set(!editTitle().trim())" />
+              @if (editTitleError()) { <p class="fr-error-text">Le titre est obligatoire.</p> }
             </div>
-            <div class="fr-input-group fr-mb-2w">
+            <div class="fr-input-group fr-mb-2w" [class.fr-input-group--error]="editVersionError()">
               <label class="fr-label" for="edit-version">Version <span style="color:var(--text-default-error)">*</span></label>
-              <input id="edit-version" class="fr-input" type="text" [value]="editVersion()" (input)="editVersion.set($any($event.target).value)" />
+              <input id="edit-version" class="fr-input" [class.fr-input--error]="editVersionError()" type="text" [value]="editVersion()"
+                     (input)="editVersion.set($any($event.target).value); editVersionError.set(false)"
+                     (blur)="editVersionError.set(!editVersion().trim())" />
+              @if (editVersionError()) { <p class="fr-error-text">La version est obligatoire.</p> }
             </div>
             <div class="fr-select-group fr-mb-2w">
               <label class="fr-label" for="edit-category">Catégorie</label>
@@ -315,6 +321,8 @@ export class ApiDetailComponent implements OnInit, OnDestroy {
   showEditModal = signal(false);
   editLoading = signal(false);
   editError = signal<string | null>(null);
+  editTitleError = signal(false);
+  editVersionError = signal(false);
   categories = signal<Category[]>([]);
   editTitle = signal('');
   editVersion = signal('');
@@ -365,6 +373,8 @@ export class ApiDetailComponent implements OnInit, OnDestroy {
     this.editContactTechnical.set(entry.contactTechnical ?? '');
     this.editAccessRights.set(entry.accessRights ?? '');
     this.editError.set(null);
+    this.editTitleError.set(false);
+    this.editVersionError.set(false);
     this.categoryService.list().subscribe((res) => this.categories.set(res.items));
     this.showEditModal.set(true);
   }
@@ -374,10 +384,9 @@ export class ApiDetailComponent implements OnInit, OnDestroy {
   }
 
   submitEdit() {
-    if (!this.editTitle().trim() || !this.editVersion().trim()) {
+    this.editTitleError.set(!this.editTitle().trim());
-      this.editError.set('Le titre et la version sont obligatoires.');
+    this.editVersionError.set(!this.editVersion().trim());
-      return;
+    if (!this.editTitle().trim() || !this.editVersion().trim()) return;
-    }
     this.editLoading.set(true);
     this.apiService.update(this.id, {
       title: this.editTitle().trim(),

front-public/src/app/pages/browse/browse.component.ts

@@ -246,13 +246,15 @@ import { forkJoin } from 'rxjs';
                   <p>{{ formError() }}</p>
                 </div>
               }
-              <div class="fr-input-group fr-mb-2w">
+              <div class="fr-input-group fr-mb-2w" [class.fr-input-group--error]="formNameError()">
                 <label class="fr-label" for="form-name">
                   Nom <span style="color:var(--text-default-error)">*</span>
                 </label>
-                <input id="form-name" class="fr-input" type="text"
+                <input id="form-name" class="fr-input" [class.fr-input--error]="formNameError()" type="text"
                        [value]="formName()"
-                       (input)="formName.set($any($event.target).value)" />
+                       (input)="formName.set($any($event.target).value); formNameError.set(false)"
+                       (blur)="formNameError.set(!formName().trim())" />
+                @if (formNameError()) { <p class="fr-error-text">Le nom est obligatoire.</p> }
               </div>
               <div class="fr-input-group fr-mb-3w">
                 <label class="fr-label" for="form-desc">
@@ -307,6 +309,7 @@ export class BrowseComponent implements OnInit {
   formName = signal('');
   formDescription = signal('');
   formError = signal<string | null>(null);
+  formNameError = signal(false);
   formLoading = signal(false);
 
   /* Ancêtres = breadcrumb sans le nœud courant (déjà dans le h1) */
@@ -346,6 +349,7 @@ export class BrowseComponent implements OnInit {
     this.formName.set('');
     this.formDescription.set('');
     this.formError.set(null);
+    this.formNameError.set(false);
     this.showFormModal.set(true);
   }
 
@@ -355,6 +359,7 @@ export class BrowseComponent implements OnInit {
     this.formName.set(cat.name);
     this.formDescription.set(cat.description ?? '');
     this.formError.set(null);
+    this.formNameError.set(false);
     this.showFormModal.set(true);
   }
 
@@ -364,9 +369,10 @@ export class BrowseComponent implements OnInit {
 
   submitForm() {
     if (!this.formName().trim()) {
-      this.formError.set('Le nom est obligatoire.');
+      this.formNameError.set(true);
       return;
     }
+    this.formNameError.set(false);
     this.formLoading.set(true);
     const name = this.formName().trim();
     const description = this.formDescription().trim() || undefined;