feat: PC5 col D embeds Insta via Behold (avec fallback profil statique)

- InstaFeed.vue (Vue island) : consomme feeds.behold.so/{feedId}, skeleton loading, grid 2x3 thumbnails, fallback profil si placeholder ou erreur
- ColInsta.astro enrichi : 2 sections @aep.politique + @julesneny, hydratation client:visible (lazy)
- .env.example committe (PUBLIC_BEHOLD_AEP/JULESNENY vides) ; .env.local deja gitignore
- docs/BEHOLD-SETUP.md : procedure inscription + recup feed IDs + alternatives + note CSP PC8

Action Jules requise (async) : inscription Behold + connexion 2 comptes Insta + remplir .env.local.

src/components/vue/InstaFeed.vue

@@ -0,0 +1,107 @@
+<script setup lang="ts">
+import { ref, onMounted } from 'vue';
+
+interface BeholdPost {
+  id: string;
+  permalink: string;
+  mediaUrl: string;
+  thumbnailUrl?: string;
+  caption?: string;
+  mediaType: 'IMAGE' | 'VIDEO' | 'CAROUSEL_ALBUM';
+  timestamp: string;
+}
+
+const props = defineProps<{
+  feedId: string;
+  account: string;
+  accountUrl: string;
+  fallbackBio?: string;
+}>();
+
+const posts = ref<BeholdPost[]>([]);
+const loading = ref(true);
+const error = ref<string | null>(null);
+
+const isPlaceholder = (id: string) => !id || id.startsWith('PLACEHOLDER_');
+
+onMounted(async () => {
+  if (isPlaceholder(props.feedId)) {
+    loading.value = false;
+    error.value = 'no-feed-id';
+    return;
+  }
+  try {
+    const controller = new AbortController();
+    const timeoutId = setTimeout(() => controller.abort(), 5000);
+    const res = await fetch(`https://feeds.behold.so/${props.feedId}`, {
+      signal: controller.signal,
+    });
+    clearTimeout(timeoutId);
+    if (!res.ok) throw new Error(`Behold returned ${res.status}`);
+    const data = await res.json();
+    const items: BeholdPost[] = Array.isArray(data) ? data : (data.posts ?? []);
+    posts.value = items.slice(0, 6);
+  } catch (e) {
+    error.value = (e as Error).message || 'fetch-error';
+  } finally {
+    loading.value = false;
+  }
+});
+</script>
+
+<template>
+  <section class="border-b border-neutral-200 last:border-b-0">
+    <header class="px-4 py-3 flex items-center justify-between">
+      <a
+        :href="accountUrl"
+        target="_blank"
+        rel="noopener"
+        class="font-medium text-sm hover:underline"
+      >
+        {{ account }}
+      </a>
+      <span v-if="loading" class="text-xs text-neutral-400">...</span>
+    </header>
+
+    <div v-if="loading" class="grid grid-cols-2 gap-1 p-1">
+      <div
+        v-for="i in 4"
+        :key="i"
+        class="aspect-square bg-neutral-100 animate-pulse"
+      />
+    </div>
+
+    <div
+      v-else-if="posts.length"
+      class="grid grid-cols-2 gap-1 p-1"
+    >
+      <a
+        v-for="post in posts"
+        :key="post.id"
+        :href="post.permalink"
+        target="_blank"
+        rel="noopener"
+        class="block aspect-square overflow-hidden group"
+      >
+        <img
+          :src="post.thumbnailUrl || post.mediaUrl"
+          :alt="post.caption?.slice(0, 80) || account"
+          loading="lazy"
+          class="w-full h-full object-cover group-hover:scale-105 transition-transform"
+        />
+      </a>
+    </div>
+
+    <div v-else class="p-4 text-sm text-neutral-600">
+      <p v-if="fallbackBio" class="mb-3">{{ fallbackBio }}</p>
+      <a
+        :href="accountUrl"
+        target="_blank"
+        rel="noopener"
+        class="inline-block px-3 py-2 bg-neutral-900 text-white rounded-lg text-sm"
+      >
+        Voir sur Instagram &rarr;
+      </a>
+    </div>
+  </section>
+</template>