feat: remove AI extensions, restructure settings, and add atomic voucher commits (#157)

Remove AI-dependent extensions (ai-chat, ai-categorization, receipt-ocr,
invoice-inbox) and their infrastructure (lib/ai/*, ai-consent, LangChain/
Anthropic/OpenAI deps) to simplify core and reduce bundle size.

Restructure monolithic settings page into dedicated sub-pages (company,
bookkeeping, invoicing, tax, banking, api, account, team, templates) with
shared layout and sidebar navigation.

Add atomic commit_journal_entry RPC so voucher number increment and status
update happen in a single transaction — prevents burned numbers on constraint
failures. Add continuity check report and voucher gap explanation tracking.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

components/settings/SecuritySettings.tsx

@@ -254,7 +254,7 @@ export function SecuritySettings() {
                   </div>
                 </div>
                 <Button
-                  onClick={() => router.push(`/mfa/enroll?returnTo=${encodeURIComponent('/settings?tab=security')}`)}
+                  onClick={() => router.push(`/mfa/enroll?returnTo=${encodeURIComponent('/settings/account')}`)}
                 >
                   <ShieldCheck className="mr-2 h-4 w-4" />
                   Aktivera 2FA