Handle variable with input flag like a variable without formula.

src/lib/components/variables/VariableHeader.svelte

@@ -23,7 +23,7 @@
   <h1 class="text-2xl font-serif font-light">
     {decomposition?.label ?? variable?.label ?? variableName}
   </h1>
-  {#if latestFormulaDate === null}
+  {#if variable?.input || latestFormulaDate === null}
     <a
       class="underline text-gray-500 hover:text-le-bleu text-xs"
       href="/variables/{variableName}">En savoir plus sur le dispositif</a