every control writes itself

The Save button is gone, and so is the SaveTarget context that announced it.
Every screen here is a preview of the thing being edited, so a change is already
visible before it is written — a button then asks somebody to confirm what they
can see.

useAutosave debounces a burst into one request. It takes the unsaved state as a
string rather than a flag, so a failed save is not retried on the next render,
and it flushes on unmount so a section change loses nothing.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/sections/AboutPanel.tsx

@@ -8,7 +8,7 @@ import { useFlash } from '../useFlash';
 import { RichText } from '../RichText';
 import { MediaField } from '../MediaField';
 import { OverlayEditor, type Overlay } from '../OverlayEditor';
-import { useSaveTarget } from '../SaveTarget';
+import { useAutosave } from '../useAutosave';
 
 /**
  * About Us — four bands, in the order the page shows them.
@@ -139,7 +139,7 @@ export const AboutPanel = () => {
     }
   };
 
-  useSaveTarget(dirty, busy !== null, save);
+  useAutosave(dirty ? 'dirty' : null, busy !== null, save);
 
   if (!about) {
     return (