Integrate dbn-legal-agent-v2: upgrade all v1 refs + add Korrespond legal-check

- Replace dbn-legal-agent with dbn-legal-agent-v2 in bootstrap.php
  (dbnToolsRunLegalCheck), DeepResearchAgent.php (interpretSeed,
  expandQueries, synthesis fallback, deploy label), BvjAnalyzerAgent.php
  (check_model label) — 8 locations total
- Add dbn-legal-agent-v2 legal threshold check to KorrespondAgent:
  called after selfCheck() in both generate() and refine(); result
  surfaced as legal_check[] in the API response
- Render legal_check card in korrespond.js using existing bvj-red-flag
  styles; shows only when non-empty
- Add .korr-legal-check CSS block in tools.css

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

assets/css/tools.css

@@ -7960,3 +7960,22 @@ body.lt-landing {
   border-bottom-color: var(--dbn-blue);
 }
 
+/* ── Korrespond legal-check card (dbn-legal-agent-v2) ────────────────────── */
+.korr-legal-check {
+  margin-top: 20px;
+  padding: 14px 16px;
+  background: rgba(186, 12, 47, 0.04);
+  border: 1px solid rgba(186, 12, 47, 0.15);
+  border-radius: 8px;
+}
+.korr-legal-check__title {
+  margin: 0 0 10px;
+  font-size: 0.92rem;
+  color: var(--ink);
+}
+.korr-legal-check__title small {
+  font-weight: 400;
+  color: var(--muted, #6b7280);
+  font-size: 0.78em;
+}
+