release(v1.7.3): lightweight boot pipeline, dramatically faster first paint, deduped /api writes, sturdier uploads/auth

public/js/defer-css.js

@@ -0,0 +1,20 @@
+// Promote any preloaded styles to real stylesheets without inline handlers (CSP-safe)
+document.addEventListener('DOMContentLoaded', () => {
+  // Promote any preloaded core CSS
+  document.querySelectorAll('link[rel="preload"][as="style"][href]').forEach(link => {
+    const href = link.getAttribute('href');
+    if ([...document.querySelectorAll('link[rel="stylesheet"]')]
+          .some(s => s.getAttribute('href') === href)) return;
+    const sheet = document.createElement('link');
+    sheet.rel = 'stylesheet';
+    sheet.href = href;
+    document.head.appendChild(sheet);
+  });
+
+
+  // Optionally load non-critical icon/extra font CSS after first paint:
+  const extra = document.createElement('link');
+  extra.rel = 'stylesheet';
+  extra.href = '/css/vendor/material-icons.css?v={{APP_QVER}}';
+  document.head.appendChild(extra);
+});