fix(bookkeeping): editable verifikationstext on andringsverifikation (#1035)

The correction header was always built server-side as
"Rattelse: <original description>". When the original entry was labelled
after the wrong account, the correction kept echoing that stale label even
after the user switched to the correct account (follow-up to the
line-description fix in #1029).

- CorrectJournalEntrySchema gains an optional trimmed description
- correctEntry() accepts options.description; blank or absent falls back
  to the canonical "Rattelse: <original>" auto text
- both correct routes (dashboard + v1, which share the schema) thread the
  description through
- CorrectionEntryDialog surfaces an editable verifikationstext field,
  pre-filled with the auto text; an untouched or cleared prefill is NOT
  sent, so the server-side fallback stays the source of truth (same
  only-overwrite-auto-filled principle as #1029)

Forward-only: already-posted corrections are immutable per BFL.

Fixes #1031

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

lib/api/schemas.ts

@@ -910,6 +910,10 @@ export const CreateJournalEntrySchema = z.object({
 })
 
 export const CorrectJournalEntrySchema = z.object({
+  // Optional verifikationstext for the corrected entry. When omitted the
+  // server falls back to "Rättelse: <original description>"; supplying it lets
+  // the user replace a header that echoed the wrong account's label (#1031).
+  description: z.string().trim().min(1, 'Description cannot be empty').optional(),
   lines: z.array(CreateJournalEntryLineSchema).min(2, 'At least two lines are required for double-entry'),
 })