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>

api/redact.php

@@ -6,11 +6,9 @@ require_once __DIR__ . '/../includes/LegalTools.php';
 dbnToolsRequireMethod('POST');
 dbnToolsRequireAuth();
 $ftUid = dbnToolsFreeTierCheck('redact');
-$ftRemaining = dbnToolsFreeTierDeduct($ftUid, 'redact');
-if ($ftRemaining >= 0) { header('X-Credits-Remaining: ' . $ftRemaining); }
 $input = dbnToolsJsonInput(400000);
 
-dbnToolsWithTelemetry('redact', '', function () use ($input): array {
+dbnToolsWithChargedTelemetry('redact', '', $ftUid, function () use ($input): array {
     $text     = dbnToolsInjectDocContent($input, dbnToolsString($input, 'text', 128000, false));
     if (mb_strlen(trim($text), 'UTF-8') < 10) {
         dbnToolsAbort('Paste text, upload a file, or select a document before running.', 422, 'empty_text');