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>

includes/KorrespondAgent.php

@@ -330,6 +330,18 @@ PROMPT;
                 $parts[] = ' • ' . $key . ': ' . $value;
             }
         }
+
+        // Inject Min Sak (private case corpus) hits if user opted in and is on a paid tier.
+        if (!empty($intake['use_my_case'])) {
+            $caseQuery = trim((string)($intake['goal'] ?? '') . ' ' . (string)($intake['narrative'] ?? ''));
+            if ($caseQuery !== '') {
+                $caseBlock = dbnToolsCaseContext(true, $caseQuery, 5);
+                if ($caseBlock !== '') {
+                    $parts[] = $caseBlock;
+                }
+            }
+        }
+
         return mb_substr(implode("\n\n", $parts), 0, self::MAX_CONTEXT_CHARS, 'UTF-8');
     }