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/upload.php

@@ -0,0 +1,50 @@
+<?php
+declare(strict_types=1);
+
+require_once __DIR__ . '/../../includes/bootstrap.php';
+require_once __DIR__ . '/../../includes/FreeTier.php';
+require_once __DIR__ . '/../../includes/CaseStore.php';
+
+dbnToolsRequireMethod('POST');
+dbnToolsRequireAuth();
+
+$userId = (int)($_SESSION['dbn_tools_sso_uid'] ?? 0);
+if ($userId <= 0) {
+    dbnToolsError('Auth required.', 401, 'auth_required');
+}
+
+if (empty($_FILES['file']) || ($_FILES['file']['error'] ?? UPLOAD_ERR_NO_FILE) !== UPLOAD_ERR_OK) {
+    dbnToolsError('No file uploaded or upload error.', 400, 'no_file');
+}
+
+$file = $_FILES['file'];
+$size = (int)$file['size'];
+$tmp  = (string)$file['tmp_name'];
+$name = (string)$file['name'];
+
+if ($size <= 0 || $size > 25 * 1024 * 1024) {
+    dbnToolsError('Filen må være mellom 1 byte og 25 MB.', 413, 'bad_size');
+}
+
+// Validate it's actually a PDF (magic number check)
+$fh = @fopen($tmp, 'rb');
+if ($fh === false) {
+    dbnToolsError('Kunne ikke lese filen.', 500, 'read_fail');
+}
+$head = (string)fread($fh, 5);
+fclose($fh);
+if (strncmp($head, '%PDF-', 5) !== 0) {
+    dbnToolsError('Filen er ikke en gyldig PDF.', 415, 'not_pdf');
+}
+
+try {
+    $doc = CaseStore::registerUpload($userId, $name, $tmp, $size);
+    CaseStore::caseEnqueueIngest((int)$doc['doc_id'], $userId);
+    dbnToolsRespond([
+        'ok' => true,
+        'doc_id' => $doc['doc_id'],
+        'filename' => $doc['filename'],
+    ]);
+} catch (Throwable $e) {
+    dbnToolsError($e->getMessage(), 400, 'upload_failed');
+}