fix(invoices): repair send dialog fiscal-period query + editable issu… (#1066)

* fix(invoices): repair send dialog fiscal-period query + editable issuance lines

The send/mark-sent dialog queried fiscal_periods with start_date/end_date
instead of period_start/period_end; the query always 400ed, and since PR
#1023 made that fatal the dialog closed instantly, blocking mark-as-sent
and email send for everyone.

Also lets accrual companies edit the proposed journal lines before booking
(both send and mark-sent), mirroring the mark-paid editor: untouched
proposals still book via the server generator; edited lines book verbatim
with balance validated at three layers. Credit notes and periodiserade
invoices keep the read-only preview. The dialog now also respects
defer_invoice_booking (#967).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(invoices): harden custom issuance-line validation per review findings

Extract the custom-line parse + balance check into a shared validator so
the send and mark-sent routes cannot drift. Reject rows carrying both
debit and credit, and 29xx interim accounts (custom lines skip accrual
schedule creation, so a 29xx balance would never be dissolved). Validate
the payload only after the invoice ownership fetch, and emit structured
log events when user-edited lines are booked or deliberately ignored, so
manual overrides are visible in audit review.

Account existence needs no route-level check: the engine already resolves
every account against the company chart and throws AccountsNotInChartError.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(invoices): address CodeRabbit findings on issuance line editing

Reject malformed JSON bodies with 400 instead of silently booking
generated lines; restrict line editing to SEK invoices (custom lines
cannot carry FX metadata); round each line before the client balance
check to match the server; stop claiming a voucher was created in the
mark-sent toast for deferred-booking companies; add programmatic labels
to the editor inputs and remove-row buttons.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

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

lib/errors/structured-errors.ts

@@ -796,6 +796,16 @@ const INVOICE: Record<string, StructuredErrorEntry> = {
     message_sv: 'Fakturan ändrades av en annan begäran. Ladda om och försök igen.',
     message_en: 'The invoice was changed by another request. Reload and retry.',
   },
+  INVOICE_MARK_SENT_LINES_UNBALANCED: {
+    httpStatus: 400,
+    message_sv: 'Verifikationsraderna är inte balanserade (debet ≠ kredit).',
+    message_en: 'Custom journal lines do not balance.',
+  },
+  INVOICE_MARK_SENT_LINES_INVALID: {
+    httpStatus: 400,
+    message_sv: 'Verifikationsraderna kan inte användas: en rad har både debet och kredit, eller använder ett interimskonto (29xx). Använd periodisering på fakturaraden istället.',
+    message_en: 'Custom journal lines are invalid: a row carries both debit and credit, or uses a 29xx interim account. Use line-level periodisering instead.',
+  },
   INVOICE_MARK_SENT_BOOK_FAILED: {
     httpStatus: 500,
     message_sv: 'Fakturan kunde inte bokföras och ligger kvar som utkast.',