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.

tests/frontend/ai.test.mjs

@@ -760,6 +760,41 @@ async function main() {
     b._panel.remove();
   });
 
+  // ── 35b. `@` captures the vault for General-mode ad-hoc context (BUG-010) ──
+  await test("mention selection stores its vault and feeds the context request", async () => {
+    localStorage.clear();
+    globalThis.fetch = async (url) => {
+      if (String(url).includes("/api/tree-search")) {
+        return {
+          ok: true, status: 200,
+          json: async () => ({ results: [{ vault: "TestVault", path: "notes/a.md", type: "file" }] }),
+        };
+      }
+      return { ok: true, status: 200, json: async () => ({}) };
+    };
+    const b = new BooksLM();
+    b._panel = b._render();
+    document.body.appendChild(b._panel);
+    b._mode = MODE.GENERAL;
+    b._vault = null;
+
+    await b._showMentionMenu("notes");
+    b._selectMention({ id: "notes/a.md", type: "file", vault: "TestVault" });
+    assert.equal(b._adhocFiles[0].vault, "TestVault", "ad-hoc entry keeps its vault");
+    assert.equal(b._contextVault(), "TestVault", "context vault derives from the ad-hoc entry");
+
+    let posted = null;
+    globalThis.fetch = async (url, opts) => {
+      if (String(url).includes("/api/ai/bookslm/context")) posted = JSON.parse(opts.body);
+      return { ok: true, status: 200, json: async () => ({ files: [], scope: "documents" }) };
+    };
+    await b._loadContext();
+    assert.equal(posted.vault, "TestVault", "context request carries the vault");
+    assert.deepEqual(posted.extra_files, ["notes/a.md"]);
+    b._panel.remove();
+    localStorage.clear();
+  });
+
   // ── 36. Capability checklist rendering (#81) ──
   await test("capability list renders checked and unchecked flags", () => {
     const caps = {