Add My Documents panel to workbench + user-docs API

- api/user-docs.php: GET/DELETE shared dbn_user_docs table (SSO users only)
  connects to dobetternorge DB via DBN_DB_* env vars
- workbench.php: My Documents panel (section 05) for SSO/free-tier users;
  shows docs uploaded from either AI chat or tools, links to AI Chat for upload
- workbench.js: fetch + render doc list, delete with Qdrant cleanup
- tools.css: workbench-docs panel + item styles
- i18n.php: my_docs_* strings in all 4 languages

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

assets/css/tools.css

@@ -6196,10 +6196,83 @@ body.lt-landing {
 }
 
 .workbench-panel--flow,
-.workbench-panel--outputs {
+.workbench-panel--outputs,
+.workbench-panel--docs {
   grid-column: 1 / -1;
 }
 
+.workbench-docs__desc {
+  font-size: 0.875rem;
+  color: var(--dbn-text-2, #555);
+  margin-bottom: 16px;
+}
+
+.workbench-docs__list {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  margin-bottom: 16px;
+  min-height: 40px;
+}
+
+.workbench-docs__item {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 8px 12px;
+  border-radius: 8px;
+  border: 1px solid var(--dbn-line, #e0ddd8);
+  background: rgba(255,255,255,0.9);
+  font-size: 0.875rem;
+}
+
+.workbench-docs__icon { flex-shrink: 0; font-size: 1rem; }
+
+.workbench-docs__name {
+  flex: 1;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  font-weight: 500;
+}
+
+.workbench-docs__meta {
+  font-size: 0.75rem;
+  color: var(--dbn-text-2, #888);
+  white-space: nowrap;
+  flex-shrink: 0;
+}
+
+.workbench-docs__remove {
+  flex-shrink: 0;
+  background: none;
+  border: 1px solid var(--dbn-line, #e0ddd8);
+  border-radius: 6px;
+  padding: 3px 10px;
+  font-size: 0.75rem;
+  cursor: pointer;
+  color: var(--dbn-text-2, #777);
+  transition: background 0.15s, color 0.15s;
+}
+
+.workbench-docs__remove:hover {
+  background: #fee2e2;
+  color: #b91c1c;
+  border-color: #fca5a5;
+}
+
+.workbench-docs__empty,
+.workbench-docs__loading {
+  font-size: 0.875rem;
+  color: var(--dbn-text-2, #888);
+  font-style: italic;
+}
+
+.workbench-docs__cta {
+  display: inline-block;
+  font-size: 0.875rem;
+}
+
 .workbench-section-head {
   display: flex;
   align-items: baseline;