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/korrespond.php

@@ -78,6 +78,7 @@ try {
                 $input['deadlines']
             ))), 0, 6) : [],
         'clarifications' => is_array($input['clarifications'] ?? null) ? $input['clarifications'] : [],
+        'use_my_case'    => !empty($input['use_my_case']),
     ];
 
     $forceDraft = !empty($input['force_draft']);