fix(arsredovisning): make the aktiekapital note completable via compa… (#1118)

* fix(arsredovisning): make the aktiekapital note completable via company settings

The annual report warned every AB that the aktiekapital note was missing
and pointed at Installningar -> Foretag, but the referenced columns
(aktiekapital, antal_aktier, kvotvarde) never existed and no settings UI
was ever built, so the warning was a dead end and no AB could produce a
complete note before Bolagsverket filing.

- migration 20260723103000: company_settings.aktiekapital (numeric) and
  antal_aktier (integer) with positive CHECKs; kvotvarde is intentionally
  not stored since ABL 1 kap 6 defines it as aktiekapital / antal aktier
- build-data.ts (K2 and K3 note paths): select only the two stored
  columns and derive kvotvarde with roundOre
- UpdateSettingsSchema: aktiekapital (positive), antal_aktier (positive
  integer), both nullable to allow clearing
- new ShareCapitalForm section on Installningar -> Foretag, rendered for
  aktiebolag only, with live derived kvotvarde display; wired through the
  existing CompanySettingsContent save path (empty string clears to null)
- sv/en strings; settings route tests (round-trip, clear, 400 on invalid);
  builder tests for derived kvotvarde and the empty-settings warning

Staging (metjnjrhvujscngnpzdv) already has the columns applied and the
note verified end-to-end against a rehearsal company.

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

* fix(arsredovisning): address PR review findings on the share-capital note

- enforce aktiekapital/antal_aktier as an all-or-nothing pair (DB CHECK,
  K2/K3 note guard now requires both, partial pair warns instead)
- numeric(15,2) column, .int() Zod constraint, maxFractionDigits 0 render
- guard numberOrNull against NaN; align kvotvarde preview with schema
- strengthen clearing test, add fractional and partial-pair tests

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

---------

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

lib/api/schemas.ts

@@ -1599,6 +1599,9 @@ export const UpdateSettingsSchema = z.object({
   tax_contact_email: z.string().email().nullable().optional().or(z.literal('')),
   fiscal_year_start_month: z.number().int().min(1).max(12).optional(),
   preliminary_tax_monthly: z.number().nullable().optional(),
+  // Share capital per Bolagsverket (annual report aktiekapital note).
+  aktiekapital: z.number().int('Aktiekapital anges i hela kronor').positive('Aktiekapital måste vara större än 0').nullable().optional(),
+  antal_aktier: z.number().int('Antal aktier måste vara ett heltal').positive('Antal aktier måste vara större än 0').nullable().optional(),
   employer_registered: z.boolean().nullable().optional(),
   employer_seasonal: z.boolean().optional(),
   bank_name: z.string().max(100, 'Banknamn får vara max 100 tecken').nullable().optional(),