feat: enable PSD2 bank integration via settings

- Uncomment Enable Banking extension in loader (now registered at runtime)
- Add subscriptionNotice field to ExtensionDefinition type
- Show confirmation dialog when enabling extensions with subscription requirements
- Fix Settings banking tab: toggle-aware visibility, URL-addressable tabs,
  BankSelector widget, correct API paths (/api/extensions/ext/enable-banking/*)
- Replace inline bank connection cards with BankConnectionStatus component
- Add actionable link to Settings from EnableBankingWorkspace
- Update CLAUDE.md with latest architecture docs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/extensions/loader.ts

@@ -14,11 +14,7 @@ import { intrastatExtension } from '@/extensions/export/intrastat'
 import { currencyReceivablesExtension } from '@/extensions/export/currency-receivables'
 import type { Extension } from './types'
 
-// ── Enable Banking (PSD2) — opt-in extension ───────────────────────────
-// Uncomment the following line to enable automatic PSD2 bank transaction sync.
-// Requires ENABLE_BANKING_APP_ID and ENABLE_BANKING_PRIVATE_KEY env vars.
-//
-// import { enableBankingExtension } from '@/extensions/general/enable-banking'
+import { enableBankingExtension } from '@/extensions/general/enable-banking'
 
 /**
  * Explicit list of first-party extensions.
@@ -36,7 +32,7 @@ const FIRST_PARTY_EXTENSIONS: Extension[] = [
   invoiceInboxExtension,
   calendarExtension,
   userDescriptionMatchExtension,
-  // enableBankingExtension,  // Uncomment to activate PSD2 bank sync
+  enableBankingExtension,
 
   // ── Export sector ──────────────────────────────────────────
   euSalesListExtension,