feat: create reusable UI components

- Add Header component with navigation and auth state
- Add Footer component with site information
- Add BIIcon component for Bootstrap Italia icons
- Add MemberDot component for member visualization
- Add default layout wrapper

Co-authored-by: Copilot <[email protected]>

app/components/Footer.vue

@@ -0,0 +1,57 @@
+<script setup lang="ts">
+import MemberDot from "~/components/MemberDot.vue";
+import { useMembers } from "~/composables/useMembers";
+
+const { sortedMembers } = useMembers();
+</script>
+
+<template>
+  <footer class="it-footer">
+    <div class="it-footer-main">
+      <div class="container">
+        <section>
+          <div class="row clearfix">
+            <div class="col-sm-12">
+              <div class="it-brand-wrapper">
+                <a href="#" data-focus-mouse="false">
+                  <svg class="icon"><use xlink:href="https://italia.github.io/bootstrap-italia/dist/svg/sprites.svg#it-code-circle"></use></svg>
+                  <div class="it-brand-text">
+                    <h2>Visione</h2>
+                    <h3 class="d-none d-md-block">Segnalazioni anonime e sicure</h3>
+                  </div>
+                </a>
+              </div>
+            </div>
+          </div>
+        </section>
+        <section class="py-4 border-white border-top">
+          <div class="row">
+            <div class="col-12 pb-2">
+              <div class="pb-2">
+                <h4>Progetto di</h4>
+                <div class="members-list d-flex justify-content-center align-items-center gap-5 flex-wrap w-100">
+                  <MemberDot
+                      v-for="member in sortedMembers"
+                      :key="member.name"
+                      :name="member.name"
+                      :image="member.image"
+                  />
+                </div>
+              </div>
+            </div>
+          </div>
+        </section>
+      </div>
+    </div>
+    <div class="it-footer-small-prints clearfix">
+      <div class="container">
+          <ul class="it-footer-small-prints-list list-inline mb-0 d-flex flex-column flex-md-row">
+            <li class="list-inline-item"><a href="#">Note legali</a></li>
+            <li class="list-inline-item"><a href="#">Privacy policy</a></li>
+            <li class="list-inline-item"><a href="/sitemap.xml">Mappa del sito</a></li>
+            <li class="list-inline-item"><a href="https://form.agid.gov.it/view/xyz">Dichiarazione di accessibilità <span class="visually-hidden">(link esterno su sito AgID)</span></a></li>
+          </ul>
+      </div>
+    </div>
+  </footer>
+</template>