Create a skill called "processreceipt".

When I upload one or more receipt photos, for each one:

1. Read the receipt and extract:
   - Date (YYYY-MM-DD). Assume Singapore DD/MM format when ambiguous. If there's no date, leave it blank and flag it.
   - Description: merchant + short summary (e.g. "Starbucks – 2 coffees"). Add the currency code if not SGD.
   - Amount: final total paid, after discounts, including tax/tip. Number only, 2 decimals.
   - Expense Category from a fixed list: Meals & Dining, Groceries, Transport, Fuel, Travel & Lodging, Office Supplies, Software & Subscriptions, Utilities, Phone & Internet, Entertainment, Health, Shopping, Other.
   If the merchant or total is unreadable, ask me. Skip anything that isn't a receipt.

2. Give each receipt a running reference number (R0001, R0002…), continuing from the highest one already used.

3. Save the original photo, unchanged, on my Mac in [ROOT FOLDER]/YYYY-MM/ (month of the receipt date, "Undated" if none), named "<Ref> - <Merchant> - <YYYY-MM-DD>.<ext>".

4. Append a row to [ROOT FOLDER]/Receipt Tracker.xlsx, sheet "Receipts", with columns Ref, Date, Description, Amount, Expense Category, File. Date must be a real Excel date, Amount a number, and File a clickable relative hyperlink to the saved photo. If the file or sheet doesn't exist yet, create it first: those six headers in row 1 as an Excel table with filters, header row frozen, Date formatted YYYY-MM-DD and Amount as 0.00.

5. Reply with a short table of what was logged and anything flagged.

Rules:
- Edit the spreadsheet in place; never rebuild it.
- If the spreadsheet is open in Excel, ask me to close it first.
- If a receipt has the same date and amount as an existing row, ask before logging.
- Never renumber existing rows or delete any files.
- If my Mac isn't reachable, stop and tell me. Don't save anywhere else.