Afegir cartells a les jams (i esquelet per a slow jams i notes)

folkugat_web/assets/templates/fragments/sessio/cartell_editor.html

@@ -0,0 +1,23 @@
+<form id="cartell-editor"
+      class="flex flex-row gap-2"
+      hx-encoding="multipart/form-data">
+    <input type='file'
+           class="border border-beige focus:outline-none
+                  rounded grow
+                  bg-brown p-1 my-1"
+            name='upload_file'/>
+    <button title="Desa els canvis"
+            class="mx-1 text-beige"
+            hx-put="/api/sessio/{{ session_id }}/cartell"
+            hx-target="#cartell-editor"
+            hx-swap="outerHTML">
+        <i class="fa fa-check" aria-hidden="true"></i>
+    </button>
+    <button title="Descarta els canvis"
+            class="mx-1 text-beige"
+            hx-get="/api/sessio/{{ session_id }}/cartell"
+            hx-target="#cartell-editor"
+            hx-swap="outerHTML">
+        <i class="fa fa-times" aria-hidden="true"></i>
+    </button>
+</form>