feat: Legal Tools v1 — multilingual landing, dashboard, SSO bridge

- Public landing page at / for unauthenticated users (EN/NO/UK/PL)
- Authenticated / shows Case Workbench dashboard with manifesto strip,
  stats, and launched-tool grid (Transcribe, Timeline, BVJ, Advocate,
  Deep Research, Corpus)
- Added includes/i18n.php with full 4-language translation layer
- Extended layout.php to Case Workbench shell with tool rail, lang switcher
- AI output language normalization extended to en/no/uk/pl in PHP agents
- SSO token validation in bootstrap.php / index.php (dobetternorge.no bridge)

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

assets/js/deep-research.js

@@ -3,7 +3,7 @@
   'use strict';
 
   const els = {};
-  let lang = 'en';
+  let lang = window.DBN_TOOLS_LANG || localStorage.getItem('dbn-ui-lang') || 'en';
   let uploadFiles = [];
   let lastResult = null;
   let branchContext = null;
@@ -102,10 +102,12 @@
 
   function bindLang() {
     els.langButtons.forEach((b) => {
+      b.classList.toggle('is-active', b.dataset.lang === lang);
       b.addEventListener('click', () => {
         els.langButtons.forEach((x) => x.classList.remove('is-active'));
         b.classList.add('is-active');
         lang = b.dataset.lang || 'en';
+        localStorage.setItem('dbn-ui-lang', lang);
       });
     });
   }