Added persistence to the search form when on search page

lib/pinchflat_web/components/layouts/app.html.heex

@@ -2,7 +2,7 @@
   <.sidebar />
 
   <div class="relative flex flex-1 flex-col overflow-y-auto overflow-x-hidden">
-    <.header />
+    <.header params={@conn.params} />
     <main>
       <div class="mx-auto max-w-screen-2xl p-4 md:p-6 2xl:p-10">
         <.flash_group flash={@flash} />

lib/pinchflat_web/components/layouts/partials/header.html.heex

@@ -20,6 +20,7 @@
           <input
             type="text"
             name="q"
+            value={@params["q"]}
             placeholder="Type to search..."
             class="w-full bg-transparent pl-9 pr-4 border-0 focus:ring-0 focus:outline-none xl:w-125"
           />