Add monetization spine + Build Your Own Case (Min Sak)

- Stripe: StripeClient.php, checkout/portal/webhook endpoints, idempotent event handling
- FreeTier: tier-aware credits (free/light/pro/pro_plus), bonus_balance, hourly caps per tier
- pricing.php + billing.php: 4-tier cards, 3 topups, Customer Portal, balance breakdown
- Min Sak: CaseStore.php, AzureDocIntelligence.php, AzureSearchAdmin.php — per-user hybrid RAG
- api/case/: upload, list, delete, ingest-callback (HMAC-auth'd from n8n)
- award-survey-credits: inter-site HMAC endpoint for dobetternorge.no survey bonus
- dashboard.php: tier badge, balance breakdown card, Min Sak CTA, survey CTA
- KorrespondAgent + all 3 other agents: use_my_case toggle wired to dbnToolsCaseContext()
- bootstrap.php: dbnToolsCaseContext(), dbnToolsIntersiteSecret(), dbnToolsCurrentTier()

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

api/case/list.php

@@ -0,0 +1,18 @@
+<?php
+declare(strict_types=1);
+
+require_once __DIR__ . '/../../includes/bootstrap.php';
+require_once __DIR__ . '/../../includes/CaseStore.php';
+
+dbnToolsRequireMethod('GET');
+dbnToolsRequireAuth();
+
+$userId = (int)($_SESSION['dbn_tools_sso_uid'] ?? 0);
+if ($userId <= 0) {
+    dbnToolsError('Auth required.', 401, 'auth_required');
+}
+
+dbnToolsRespond([
+    'ok' => true,
+    'docs' => CaseStore::listDocs($userId),
+]);