Add NOK pricing catalog, credit ledger, success-based charging, and tier-gated model routing

- PricingCatalog.php: single source of truth for plans (free/plus/pro), top-ups,
  Stripe price env keys, tool costs (0–6 credits), STT variable billing, feature limits
- FreeTier.php: monthly-first credit deduction, ledger (user_tool_credit_ledger),
  STT reservation/settle/release, monthly reset, trial logic
- StripeClient.php: canonical SKUs (plus/pro/topup_100/300/1000), legacy aliases kept
- stripe-checkout.php: subscription vs payment mode, trial gating, catalog metadata
- stripe-webhook.php: idempotent via stripe_events, handles subscription lifecycle +
  invoice.paid renewal + one-time topup credit grants
- All API tools: success-based credit deduction (check before, charge after)
- transcribe.php: file-size heuristic reservation, settle from actual provider duration
- ask.php + LegalTools.php: ToolModels engine resolution — Pro gets gpt-4o
- KorrespondAgent.php + korrespond.php: tier-gated draft deployment —
  Free/Plus gets gpt-4o-mini, Pro gets gpt-4o
- pricing.php: NOK-only, plan cards, top-up packs, Organisation contact card,
  tool cost table, separate monthly/prepaid balance display
- 003_pricing_credit_catalog.sql: ledger and STT reservation tables

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

dashboard.php

@@ -60,7 +60,7 @@ window.DBN_TOOLS_LANG = <?= json_encode($uiLang, JSON_UNESCAPED_UNICODE) ?>;
                 <?php $eff = (int)$dashDetail['balance'] + (int)$dashDetail['bonus_balance']; ?>
                 <?= number_format($eff, 0, ',', ' ') ?>
             </p>
-            <p style="margin:0; color:#6b7280; font-size:0.85rem;"><?= (int)$dashDetail['balance'] ?> <?= htmlspecialchars(dbnToolsT('credits_monthly', $uiLang)) ?> · <?= (int)$dashDetail['bonus_balance'] ?> <?= htmlspecialchars(dbnToolsT('credits_bonus', $uiLang)) ?> · <a href="/billing.php"><?= htmlspecialchars(dbnToolsT('details_link', $uiLang)) ?></a></p>
+            <p style="margin:0; color:#6b7280; font-size:0.85rem;"><?= (int)$dashDetail['balance'] ?> <?= htmlspecialchars(dbnToolsT('credits_monthly', $uiLang)) ?> · <?= (int)$dashDetail['bonus_balance'] ?> <?= $uiLang === 'no' ? 'forhåndsbetalte' : 'prepaid' ?> · <a href="/billing.php"><?= htmlspecialchars(dbnToolsT('details_link', $uiLang)) ?></a></p>
         </div>
         <?php if (in_array($dashTier, ['plus','pro'], true)): ?>
         <a class="status-card" href="/min-sak.php" style="background:#fff; border:1px solid #e5e7eb; border-radius:10px; padding:1.1rem 1.25rem; text-decoration:none; color:inherit;">