v3: code quality and visual consistency pass (refactored all forms across the app), fixed filename-related upload bug

src/components/form/SubmitButton.tsx

@@ -0,0 +1,30 @@
+import type { ReactNode } from "react";
+import { useFormState } from "react-hook-form";
+
+interface SubmitButtonProps {
+  children: ReactNode;
+  /** Replaces the label while the form is submitting (e.g. "Saving…"). */
+  pendingLabel?: ReactNode;
+  disabled?: boolean;
+  className?: string;
+}
+
+/**
+ * Submit button that reflects react-hook-form's `isSubmitting` from the
+ * surrounding `FormProvider`: it disables itself while submitting and swaps in
+ * `pendingLabel`. Standardizes the hand-rolled "Save → Saving…" pattern.
+ */
+export function SubmitButton({
+  children,
+  pendingLabel,
+  disabled,
+  className = "btn-primary",
+}: SubmitButtonProps) {
+  const { isSubmitting } = useFormState();
+
+  return (
+    <button type="submit" className={className} disabled={isSubmitting || disabled}>
+      {isSubmitting && pendingLabel != null ? pendingLabel : children}
+    </button>
+  );
+}