fix(ai): lisibilite des modeles + contexte @ en mode General (BUG-010, BUG-011)

BUG-011: popover des modeles aligne a droite (right:0), largeur 340px bornee, noms sur plusieurs lignes + title. BUG-010: la selection @ capture le vault renvoye par tree-search et _contextVault() le propage aux requetes /context et /chat, corrigeant le contexte ad-hoc en mode General.

frontend/js/ai.js

@@ -187,9 +187,9 @@ async function _buildPickerUI() {
   modelPop.className = 'ai-picker-model-pop hidden';
   // Critical layout is applied inline too: if a stale stylesheet is served, the
   // popover must still stack vertically instead of flowing as a block of text.
-  modelPop.style.cssText = 'position:absolute;top:calc(100% + 4px);left:0;z-index:60;'
-    + 'min-width:220px;max-width:320px;background:var(--bg-primary);border:1px solid var(--border);'
-    + 'border-radius:8px;box-shadow:0 8px 24px rgba(0,0,0,0.35);padding:6px;';
+  modelPop.style.cssText = 'position:absolute;top:calc(100% + 4px);right:0;z-index:60;'
+    + 'min-width:220px;width:340px;max-width:calc(100vw - 24px);background:var(--bg-primary);'
+    + 'border:1px solid var(--border);border-radius:8px;box-shadow:0 8px 24px rgba(0,0,0,0.35);padding:6px;';
 
   const modelSearch = document.createElement('input');
   modelSearch.type = 'text';
@@ -296,7 +296,8 @@ async function _buildPickerUI() {
       option.className = 'ai-picker-model-option';
       option.dataset.value = model;
       option.textContent = model || t('ai.model_default');
-      option.style.cssText = 'display:block;width:100%;text-align:left;';
+      option.title = model;
+      option.style.cssText = 'display:block;width:100%;text-align:left;white-space:normal;overflow-wrap:anywhere;';
       if (model === modelSelect.value) option.classList.add('active');
       option.addEventListener('mousedown', (e) => { e.preventDefault(); _pick(model); });
       modelList.appendChild(option);