EtchASketch: Manifest, icon and mutex fixes

etch_a_sketch/application.fam

@@ -1,6 +1,6 @@
 App(
     appid="etch",
-    name="Etch A Sketch",
+    name="Etch a Sketch",
     apptype=FlipperAppType.EXTERNAL,
     entry_point="etch_a_sketch_app",
     cdefines=["APP_ETCH_A_SKETCH"],
@@ -8,5 +8,5 @@ App(
     stack_size=2 * 1024,
     order=175,
     fap_icon="etch-a-sketch-icon.png",
-    fap_category="Misc",
+    fap_category="Media",
 )