feat(export): batch wafer-map PNG export from file list

- BatchExport worker + BatchExportController (threaded, busy flag)
- SourcePanel: Export Maps button → FolderDialog → batch export
  with progress/summary banner (dismissible)
- StreamControlPanel: name single export after loaded CSV + timestamp

src/pygui/ISC/Tabs/icons/images.svg

@@ -0,0 +1,16 @@
+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <path d="M18 22H4a2 2 0 0 1-2-2V6" />
+  <path d="m22 13-1.296-1.296a2.41 2.41 0 0 0-3.408 0L11 18" />
+  <circle cx="12" cy="8" r="2" />
+  <rect width="16" height="16" x="6" y="2" rx="2" />
+</svg>