feat: optimize profile image sizes, silent PWA updates, storage cleanup fixes

- Resize avatars/icons to 256px and banners to 1280px (client crop + server safety net)
- Add server-side resizeProfileImage() for federation/API uploads without crop modal
- Fix unconstrained crop on RegisterPage and CreateSpace (was missing maxOutputDimension)
- PWA: switch to autoUpdate with skipWaiting/clientsClaim for seamless deploys
- Storage janitor: exclude profile images from unlinked cleanup, delete stale thumbnails
- Add deleteAttachmentByFilename() to clean orphaned attachment records for profile images
- Migration: one-time cleanup of stale profile image attachment records
- GeneralPanel: wrap in <form> to prevent implicit submission

packages/web/index.html

@@ -6,7 +6,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <meta name="description" content="Self-hosted chat platform" />
     <meta name="theme-color" content="#0b0b10" />
-    <meta name="apple-mobile-web-app-capable" content="yes" />
+    <meta name="mobile-web-app-capable" content="yes" />
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
     <meta name="apple-mobile-web-app-title" content="Backspace" />
     <link rel="icon" type="image/png" sizes="32x32" href="/icons/favicon-32.png" />