rajoute le support de l'utilisation de markdown (sur un sous-ensemble) dans la description des campagnes et des propositions

src/components/CreateCampaignModal.tsx

@@ -2,10 +2,10 @@
 import { useState } from 'react';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
-import { Textarea } from '@/components/ui/textarea';
 import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from '@/components/ui/dialog';
 import { Label } from '@/components/ui/label';
 import { campaignService } from '@/lib/services';
+import { MarkdownEditor } from '@/components/MarkdownEditor';
 
 interface CreateCampaignModalProps {
   isOpen: boolean;
@@ -160,18 +160,13 @@ export default function CreateCampaignModal({ isOpen, onClose, onSuccess }: Crea
             />
           </div>
           
-          <div className="space-y-2">
-            <Label htmlFor="description">Description *</Label>
-            <Textarea
-              id="description"
-              name="description"
-              value={formData.description}
-              onChange={handleChange}
-              placeholder="Décrivez l'objectif de cette campagne..."
-              rows={3}
-              required
-            />
-          </div>
+          <MarkdownEditor
+            value={formData.description}
+            onChange={(value) => setFormData(prev => ({ ...prev, description: value }))}
+            placeholder="Décrivez l'objectif de cette campagne..."
+            label="Description *"
+            maxLength={2000}
+          />
           
           <div className="space-y-2">
             <Label htmlFor="budget_per_user">Budget (€) *</Label>