Add My Docs picker to deep-research, advocate, barnevernet, korrespond, citations

- PHP: Add docPickerSection (button + chips + hidden input) to all 5 tool pages
- JS: Send doc_ids in payload for deep-research, advocate, barnevernet, korrespond
- Backend: Inject selected corpus doc content into paste_text/narrative/notes via dbnToolsInjectDocContent
- Citations: Add upload zone (file → api/extract.php → textarea) + paste textarea with live Norwegian legal reference extraction (regex) + ref chips → title search; doc picker populates titleInput via MutationObserver

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

assets/js/barnevernet.js

@@ -410,6 +410,8 @@
       additional_notes: additionalNotes,
       use_my_case:      (typeof window.dbnGetUseMyCase === 'function') ? window.dbnGetUseMyCase() : false,
     };
+    const _bvjDocIds = (document.getElementById('docPickerIds')?.value || '').split(',').map(Number).filter(Boolean);
+    if (_bvjDocIds.length) payload.doc_ids = _bvjDocIds;
 
     if (branchContext) {
       payload.prior_context = branchContext;