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/utils/documentPreview.js

@@ -0,0 +1,29 @@
+import { getFileIcon } from './fileIcons'
+
+export const getPreviewType = (document) => {
+  if (!document) { return null }
+  const mime = (document.mimeType || '').toLowerCase()
+
+  if (mime.startsWith('image/')) { return 'image' }
+  if (mime === 'application/pdf') { return 'pdf' }
+  if (mime.startsWith('audio/')) { return 'audio' }
+  if (mime.startsWith('video/')) { return 'video' }
+  if (mime.startsWith('text/') || mime.includes('json') || mime.includes('xml')) { return 'text' }
+  return null
+}
+
+export const canPreviewDocument = (document = {}) => {
+  if (!getPreviewType(document)) return false
+  return !!(document.fileUrl || document.path)
+}
+
+export const isImageDocument = (document = {}) => getPreviewType(document) === 'image'
+
+export const isPdfDocument = (document = {}) => getPreviewType(document) === 'pdf'
+
+export const describeDocument = (document) => {
+  if (!document) { return '' }
+  const name = document.filename || document.name || ''
+  const icon = getFileIcon({ name, mime: document.mimeType })
+  return icon.label
+}