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/app.vue

@@ -0,0 +1,63 @@
+<template>
+  <div class="min-h-screen flex flex-col bg-base-200/40">
+    <!-- Subtle dot pattern background -->
+    <div class="fixed inset-0 -z-10 bg-[radial-gradient(oklch(85%_0.02_260)_1px,transparent_1px)] bg-[size:24px_24px] opacity-40" />
+
+    <AppNavbar
+      @open-settings="displaySettingsOpen = true"
+      @logout="handleLogout"
+    />
+
+    <main class="flex-1">
+      <NuxtPage :transition="{ name: 'page', mode: 'out-in' }" />
+    </main>
+
+    <ToastContainer />
+
+    <ConfirmModal />
+
+    <DisplaySettings
+      :is-open="displaySettingsOpen"
+      @close="displaySettingsOpen = false"
+      @update-settings="handleSettingsUpdate"
+    />
+
+    <footer class="border-t border-base-300/50 bg-base-100/60 backdrop-blur-sm">
+      <div class="container mx-auto flex items-center justify-between px-6 py-3">
+        <p class="text-xs text-base-content/40 font-medium tracking-wide">
+          &copy; Malio {{ new Date().getFullYear() }}
+        </p>
+        <NuxtLink
+          to="/changelog"
+          class="text-xs text-base-content/40 hover:text-primary transition-colors font-medium"
+        >
+          v{{ appVersion }}
+        </NuxtLink>
+      </div>
+    </footer>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { ref, computed, onMounted } from 'vue'
+import { navigateTo, useRuntimeConfig } from '#imports'
+import { useProfileSession } from '~/composables/useProfileSession'
+
+const displaySettingsOpen = ref(false)
+const { ensureSession, logout } = useProfileSession()
+const runtimeConfig = useRuntimeConfig()
+const appVersion = computed(() => (runtimeConfig.public?.appVersion as string) ?? '0.1.0')
+
+const handleSettingsUpdate = (_settings: unknown) => {
+  // Placeholder for future persistence
+}
+
+const handleLogout = async () => {
+  await logout()
+  await navigateTo('/profiles')
+}
+
+onMounted(async () => {
+  await ensureSession()
+})
+</script>