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/DiscrepancyAgent.php

@@ -754,9 +754,10 @@ PROMPT;
         $locale      = dbnToolsLanguageName($language);
         $sourceCount = count($numberedSources);
         $deployLabel = match ($engine) {
-            'gpu'        => 'GPU (cuttlefish)',
-            'azure_full' => 'gpt-4o',
-            default      => $this->azure->chatDeployment(),
+            'gpu'          => 'GPU (cuttlefish)',
+            'dbn_legal_v3' => 'dbn-legal-agent-v3',
+            'azure_full'   => 'gpt-4o',
+            default        => $this->azure->chatDeployment(),
         };
 
         if (empty($numberedSources)) {
@@ -863,7 +864,10 @@ PROMPT;
 
         $raw = '';
         try {
-            if ($engine === 'gpu') {
+            if ($engine === 'dbn_legal_v3') {
+                $response = dbnToolsCallGpuLlm($messages, array_merge($opts, ['model' => 'dbn-legal-agent-v3', 'timeout' => 180]));
+                $raw = (string)($response['choices'][0]['message']['content'] ?? '');
+            } elseif ($engine === 'gpu') {
                 $response = dbnToolsCallGpuLlm($messages, $opts);
                 $raw = (string)($response['choices'][0]['message']['content'] ?? '');
             } elseif ($engine === 'azure_full') {