feat(lanes): add lane tools menu and header liveness/age indicator

Move the rare destructive lane actions behind a LaneToolsMenu next to
the lane header, and show a liveness dot + status label + stage age
inline in the header instead of only in the card grid.

client/src/pages/__tests__/__snapshots__/screens.snapshot.test.tsx.snap

@@ -5735,31 +5735,35 @@ exports[`screen snapshots > Run 1`] = `
           running
         </span>
       </div>
-      <button
-        class="ml-auto flex items-center gap-1.5 rounded border border-border-light px-3 py-1 text-xs text-fg-secondary transition-colors hover:border-border-light hover:text-fg-primary"
-        title="Create a lane from a working directory"
+      <div
+        class="ml-auto flex items-center gap-2"
       >
-        <svg
-          class="lucide lucide-plus h-3.5 w-3.5"
-          fill="none"
-          height="24"
-          stroke="currentColor"
-          stroke-linecap="round"
-          stroke-linejoin="round"
-          stroke-width="2"
-          viewBox="0 0 24 24"
-          width="24"
-          xmlns="http://www.w3.org/2000/svg"
+        <button
+          class="flex items-center gap-1.5 rounded border border-border-light px-3 py-1 text-xs text-fg-secondary transition-colors hover:border-border-light hover:text-fg-primary"
+          title="Create a lane from a working directory"
         >
-          <path
-            d="M5 12h14"
-          />
-          <path
-            d="M12 5v14"
-          />
-        </svg>
-        Add lane
-      </button>
+          <svg
+            class="lucide lucide-plus h-3.5 w-3.5"
+            fill="none"
+            height="24"
+            stroke="currentColor"
+            stroke-linecap="round"
+            stroke-linejoin="round"
+            stroke-width="2"
+            viewBox="0 0 24 24"
+            width="24"
+            xmlns="http://www.w3.org/2000/svg"
+          >
+            <path
+              d="M5 12h14"
+            />
+            <path
+              d="M12 5v14"
+            />
+          </svg>
+          Add lane
+        </button>
+      </div>
     </div>
     <div
       class="flex min-h-0 flex-1 flex-col gap-4"