Feature request: create employee expense claims (utlegg/reiseregning) + attach receipt

The hosted MCP (mcp.tripletex.no) has no write path for employee out-of-pocket
expenses. On the expense side today you can:

• search/read supplier invoices (search_supplier_invoices, get_supplier_invoice)
• count the voucher reception (get_voucher_inbox_count — no item-level access)
• create a supplier (execute_supplier)

…but there's no way to create an utlegg / reiseregning / travel expense or to
upload a receipt (PDF/PNG). So an assistant can read and approve supplier
invoices, but can't file the thing employees most often automate.

Request: expose travel-expense writes, mirroring the REST /v2/travelExpense:

• create_travel_expense (employee, date, purpose, optional project/department)
• add_travel_expense_cost (amount, currency, category/account, VAT)
• attach_travel_expense_receipt (PDF/PNG/JPEG upload)
• submit / deliver for approval
• search_travel_expenses / get_travel_expense (status + idempotency)

Start by reading the existing supplier-invoice and supplier tools, then compare their patterns with the REST /v2/travelExpense endpoint. Define how the requested create, cost, receipt-upload, submission, search, and retrieval operations fit the MCP surface; done means the full expense lifecycle and PDF/PNG/JPEG receipt path are exposed with status and idempotency support.