Validation fixes for vendor editing
xpenser tightened vendor edit validation so merchant records stay consistent when users update vendor information.

Vendor editing became safer with validation improvements for merchant-related data.
This release came from PR #23 and is now part of the xpenser release archive. It gives people evaluating an open-source expense tracker a clearer view of how the product has improved over time.
What changed
- Improved validation around vendor edit flows.
- Protected merchant data consistency during updates.
- Kept vendor analytics from receiving malformed labels.
Why it matters
Vendor analytics depend on clean merchant data. Validation fixes prevent small edit mistakes from weakening reports later.
Where it fits
This release supports the vendor and merchant analysis work added around the same time.
For a broader product overview, start with the xpenser home page. Developers can also explore the personal finance API and MCP tools, while self-hosters can review the self-hosted personal finance tracker page.