refactor : merge Inventory_frontend submodule into frontend/ directory

Merges the full git history of Inventory_frontend into the monorepo
under frontend/. Removes the submodule in favor of a unified repo.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/app/components/DetailHeader.vue

@@ -0,0 +1,51 @@
+<template>
+  <div class="flex flex-col gap-4 md:flex-row md:items-start md:justify-between">
+    <div class="flex flex-col gap-2">
+      <h1 class="text-3xl font-bold">{{ title }}</h1>
+      <p v-if="subtitle" class="text-sm text-base-content/70">{{ subtitle }}</p>
+    </div>
+    <div class="flex items-center gap-2">
+      <button
+        v-if="canEdit"
+        class="btn btn-primary"
+        :class="{ 'btn-outline': isEditMode }"
+        @click="$emit('toggle-edit')"
+      >
+        <IconLucideSquarePen v-if="!isEditMode" class="w-5 h-5 mr-2" aria-hidden="true" />
+        <IconLucideEye v-else class="w-5 h-5 mr-2" aria-hidden="true" />
+        {{ isEditMode ? 'Voir détails' : 'Modifier' }}
+      </button>
+      <button type="button" class="btn btn-ghost btn-sm md:btn-md" @click="goBack">
+        Retour au catalogue
+      </button>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+import IconLucideSquarePen from '~icons/lucide/square-pen'
+import IconLucideEye from '~icons/lucide/eye'
+
+const router = useRouter()
+
+const props = defineProps<{
+  title: string
+  subtitle?: string
+  isEditMode: boolean
+  canEdit: boolean
+  backLink: string
+}>()
+
+defineEmits<{
+  'toggle-edit': []
+}>()
+
+function goBack() {
+  if (window.history.length > 1) {
+    router.back()
+  }
+  else {
+    navigateTo(props.backLink)
+  }
+}
+</script>