feat: add background image upload to banner builder

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/bannieres/BannerBuilder.tsx

@@ -48,6 +48,9 @@ export function BannerBuilder({ onApply, onClose }: Props) {
   const [price, setPrice] = useState('')
   const [comparePrice, setComparePrice] = useState('')
   const [selectedImageUrl, setSelectedImageUrl] = useState<string | null>(null)
+  const [backgroundBlob, setBackgroundBlob] = useState<Blob | null>(null)
+  const [backgroundPreview, setBackgroundPreview] = useState<string | null>(null)
+  const bgFileRef = useRef<HTMLInputElement>(null)
 
   // Generation
   const [rendering, setRendering] = useState(false)
@@ -112,6 +115,22 @@ export function BannerBuilder({ onApply, onClose }: Props) {
     }
   }
 
+  const handleBgFile = (e: React.ChangeEvent<HTMLInputElement>) => {
+    const file = e.target.files?.[0]
+    if (!file) return
+    setBackgroundBlob(file)
+    const url = URL.createObjectURL(file)
+    if (backgroundPreview) URL.revokeObjectURL(backgroundPreview)
+    setBackgroundPreview(url)
+    e.target.value = ''
+  }
+
+  const removeBg = () => {
+    if (backgroundPreview) URL.revokeObjectURL(backgroundPreview)
+    setBackgroundBlob(null)
+    setBackgroundPreview(null)
+  }
+
   const getConfig = useCallback((): BannerConfig => ({
     scheme,
     promoLabel,
@@ -119,7 +138,8 @@ export function BannerBuilder({ onApply, onClose }: Props) {
     price,
     comparePrice,
     productImageUrl: selectedImageUrl,
-  }), [scheme, promoLabel, title, price, comparePrice, selectedImageUrl])
+    backgroundImageBlob: backgroundBlob,
+  }), [scheme, promoLabel, title, price, comparePrice, selectedImageUrl, backgroundBlob])
 
   const generate = useCallback(async () => {
     setRendering(true)
@@ -142,7 +162,7 @@ export function BannerBuilder({ onApply, onClose }: Props) {
     if (!title && !product) return
     const t = setTimeout(() => { generate() }, 600)
     return () => clearTimeout(t)
-  }, [scheme, promoLabel, title, price, comparePrice, selectedImageUrl]) // eslint-disable-line react-hooks/exhaustive-deps
+  }, [scheme, promoLabel, title, price, comparePrice, selectedImageUrl, backgroundBlob]) // eslint-disable-line react-hooks/exhaustive-deps
 
   const applyToSlide = async () => {
     if (!previewRef.current) return
@@ -248,9 +268,40 @@ export function BannerBuilder({ onApply, onClose }: Props) {
               )}
             </section>
 
+            {/* Image de fond */}
+            <section>
+              <h3 className="text-xs font-semibold text-gray-300 uppercase tracking-wide mb-2">Image de fond</h3>
+              {backgroundPreview ? (
+                <div className="relative rounded overflow-hidden border border-slate-600">
+                  <img src={backgroundPreview} alt="Fond" className="w-full h-24 object-cover" />
+                  <button
+                    type="button"
+                    onClick={removeBg}
+                    className="absolute top-1 right-1 bg-black/70 hover:bg-red-900 text-white text-xs px-1.5 py-0.5 rounded"
+                  >
+                    ✕ Retirer
+                  </button>
+                </div>
+              ) : (
+                <button
+                  type="button"
+                  onClick={() => bgFileRef.current?.click()}
+                  className="w-full py-3 border-2 border-dashed border-slate-600 hover:border-indigo-500 rounded text-xs text-slate-400 hover:text-indigo-400 transition-colors"
+                >
+                  + Uploader une image de fond
+                </button>
+              )}
+              <input ref={bgFileRef} type="file" accept="image/*" className="hidden" onChange={handleBgFile} />
+              {backgroundPreview && (
+                <p className="text-xs text-slate-500 mt-1">Un overlay sombre est appliqué automatiquement pour la lisibilité du texte.</p>
+              )}
+            </section>
+
             {/* Thème couleur */}
             <section>
-              <h3 className="text-xs font-semibold text-gray-300 uppercase tracking-wide mb-2">Thème couleur</h3>
+              <h3 className="text-xs font-semibold text-gray-300 uppercase tracking-wide mb-2">
+                {backgroundPreview ? 'Couleur du texte' : 'Thème couleur'}
+              </h3>
               <div className="grid grid-cols-2 gap-1.5">
                 {schemeEntries.map(([key, s]) => (
                   <button