docs(admin): update guide for Excel import and hamburger sidebar

- Replace Cantaloupe Sync section with Excel Import section
- Update troubleshooting tips for import (not sync)
- Mention hamburger menu in mobile description

docs/ADMIN_GUIDE.md

@@ -1,6 +1,6 @@
 # Canteen Admin Panel — User Guide
 
-> Administrative interface for managing customers, locations, users, geofences, settings, and Cantaloupe data sync. Designed for desktop but mobile-responsive (screenshots from Pixel 9a).
+> Administrative interface for managing customers, locations, users, geofences, settings, and Excel data imports. Designed for desktop but mobile-responsive with a hamburger menu on phones (screenshots from Pixel 9a).
 
 ## Table of Contents
 
@@ -125,21 +125,19 @@ Manage these lookup tables:
 
 ---
 
-## 7. Cantaloupe Data Sync
+## 7. Excel Import
 
-Navigate to **🔄 Sync** in the sidebar.
+Navigate to **📥 Import** in the sidebar.
 
-![Cantaloupe Sync](images/p9a_admin_sync.png)
-
-The Cantaloupe Sync page lets you import asset data from the Cantaloupe vending management system.
+The Import page lets you upload asset data from Excel files (Cantaloupe exports or other structured spreadsheets).
 
 ### How it Works
 
-1. **Sync Now** button — Downloads the latest Excel export from Cantaloupe and creates a pending import batch
-2. **Upload Excel File** — Manually upload a Cantaloupe Excel export file
+1. Click **📤 Upload Excel** and select your `.xlsx` or `.xls` file
+2. The system parses the file, maps columns, and creates a **pending import batch**
 3. **Review Changes** — Each batch shows new, changed, and removed assets with field-level diffs
 4. **Approve** — Apply the changes to live data
-5. **Reject** — Discard the batch
+5. **Reject** — Discard the batch if the data looks wrong
 
 ### Import History
 
@@ -171,12 +169,12 @@ Available at the bottom of the sidebar:
 
 ## 9. Tips & Troubleshooting
 
-### Cantaloupe Sync Fails
+### Import Fails
 
-1. Check the credentials in the Cantaloupe downloader config
-2. The server must have network access to mycantaloupe.com
-3. Check the error message in the sync batch detail view
-4. Try the **Upload Excel File** option as a fallback
+1. Make sure your Excel file has a header row and at least one data row
+2. The system maps columns by keyword matching — check that column headers contain recognizable terms like "Asset ID", "Name", etc.
+3. Check the error message displayed after upload
+4. Try exporting from Cantaloupe to Excel first, then upload the file manually
 
 ### Admin Panel Not Loading