v1.6.8: remove offer exchange rate, add invoice item description, offer filters, table animations

- Remove exchange_rate and exchange_rate_date from quotations (schema, service, PDF, form)
- Add item_description field to invoice_items (schema, migration, service, form, PDF)
- Add offer status/customer/order filters with tab-based UI
- Clean up offer statuses to active/ordered/invalidated
- Allow invalidate action for non-ordered offers (not just expired)
- Add fade animations on offers and invoices table data changes

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/schemas/invoices.schema.ts

@@ -2,6 +2,7 @@ import { z } from "zod";
 
 const InvoiceItemSchema = z.object({
   description: z.string().nullish(),
+  item_description: z.string().nullish(),
   quantity: z
     .union([z.number(), z.string()])
     .transform((v) => {