fix: session panel wider + two-line layout for session names

Root cause: 300px panel minus edit btn (28px) + meta (~130px) + delete
btn (28px) + gaps/padding left only ~70px (~7 chars) for the session name.

- Panel: 300px → 420px desktop, 300px → 380px mobile drawer
- Max-height: 340px → 400px
- Session item: name and meta now in a .session-body flex column, so the
  name gets full body width (panel minus two buttons) — meta lives below
- Edit mode: hides .session-body + delete, input takes the full body slot

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

cortex/static/style.css

@@ -278,8 +278,8 @@
             position: absolute;
             top: calc(100% + 4px);
             right: 12px;
-            width: min(300px, calc(100vw - 24px));
-            max-height: 340px;
+            width: min(420px, calc(100vw - 24px));
+            max-height: 400px;
             overflow-y: auto;
             background: var(--surface);
             border: 1px solid var(--border);
@@ -291,19 +291,26 @@
         #sessions-panel.open { display: block; }
 
         .session-item {
-            padding: 10px 14px;
+            padding: 8px 12px;
             cursor: pointer;
             border-bottom: 1px solid var(--border);
             display: flex;
-            justify-content: space-between;
             align-items: center;
-            gap: 8px;
+            gap: 6px;
         }
 
         .session-item:last-child { border-bottom: none; }
         .session-item:hover { background: var(--bg); }
         .session-item.new { color: var(--accent); justify-content: center; }
 
+        .session-body {
+            flex: 1;
+            min-width: 0;
+            display: flex;
+            flex-direction: column;
+            gap: 2px;
+        }
+
         .session-delete-btn {
             background: none;
             border: none;
@@ -380,11 +387,9 @@
         }
 
         .session-meta {
-            font-size: 0.78rem;
+            font-size: 0.75rem;
             color: var(--muted);
             white-space: nowrap;
-            text-align: right;
-            flex-shrink: 0;
         }
 
         /* Messages */
@@ -1590,7 +1595,7 @@
                 top: 0;
                 right: 0;
                 bottom: 0;
-                width: min(300px, 85vw);
+                width: min(380px, 90vw);
                 max-height: none;
                 height: 100%;
                 border-radius: 0;