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/composables/useEntityHistory.ts

@@ -0,0 +1,70 @@
+/**
+ * Generic entity history composable.
+ *
+ * Replaces useComponentHistory, usePieceHistory, useProductHistory which were
+ * 99% identical (only the API endpoint differed).
+ */
+
+import { ref } from 'vue'
+import { useApi } from '~/composables/useApi'
+
+export type EntityHistoryActor = {
+  id: string
+  label: string
+}
+
+export type EntityHistoryEntry = {
+  id: string
+  action: 'create' | 'update' | 'delete' | string
+  createdAt: string
+  actor: EntityHistoryActor | null
+  diff: Record<string, { from: unknown; to: unknown }> | null
+  snapshot: Record<string, unknown> | null
+}
+
+const ENTITY_ENDPOINTS: Record<string, string> = {
+  machine: '/machines',
+  composant: '/composants',
+  piece: '/pieces',
+  product: '/products',
+}
+
+const extractItems = (payload: any): EntityHistoryEntry[] => {
+  if (Array.isArray(payload?.items)) return payload.items
+  if (Array.isArray(payload?.member)) return payload.member
+  if (Array.isArray(payload?.['hydra:member'])) return payload['hydra:member']
+  return []
+}
+
+export function useEntityHistory(entityType: 'machine' | 'composant' | 'piece' | 'product') {
+  const { get } = useApi()
+  const basePath = ENTITY_ENDPOINTS[entityType]
+
+  const history = ref<EntityHistoryEntry[]>([])
+  const loading = ref(false)
+  const error = ref<string | null>(null)
+
+  const loadHistory = async (entityId: string) => {
+    loading.value = true
+    error.value = null
+    try {
+      const result = await get(`${basePath}/${entityId}/history`)
+      if (!result.success) {
+        error.value = result.error ?? 'Impossible de charger l\'historique.'
+        history.value = []
+        return result
+      }
+      history.value = extractItems(result.data)
+      return { success: true, data: history.value }
+    } catch (err: any) {
+      const message = err?.message ?? 'Erreur inconnue'
+      error.value = message
+      history.value = []
+      return { success: false, error: message }
+    } finally {
+      loading.value = false
+    }
+  }
+
+  return { history, loading, error, loadHistory }
+}