feat(260923-lrr): Web — versionierte Symbol-Adresse, Datei-Auswahl, Entfernen-Knopf

- favorites-api.ts: FavoriteRequestError (Grund iconUrlUnreachable/iconTooLarge/
  iconInvalidType/iconUploadFailed), uploadFavoriteIcon/removeFavoriteIcon,
  FAVORITE_ICON_MAX_BYTES, Felder uploadedIconMime/iconVersion
- favorites-widget.tsx: Proxy-Bild traegt ?v=<iconVersion> (Cache-Bust nach
  Aenderung), Remount-Key um iconVersion/uploadedIconMime erweitert, eigenes
  Symbol im Hinzufuegen- und Bearbeitungsformular waehlen, Entfernen-Knopf,
  Fehlermeldung (role=alert) im Formular, Platzhalter jetzt uebersetzbar
- de.json/en.json: neun neue Texte unter widgets.favorites
- CHANGELOG.md und Anwenderhandbuch ergaenzt

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/src/messages/en.json

@@ -336,7 +336,16 @@
       "error": "Error loading favorites",
       "titleLabel": "Title",
       "titlePlaceholder": "Title (optional)",
-      "viewModeLabel": "Switch view"
+      "viewModeLabel": "Switch view",
+      "iconUrlPlaceholder": "Logo URL (optional)",
+      "iconUploadLabel": "Upload custom icon",
+      "iconUploadHint": "PNG, JPEG, GIF, WebP, ICO or SVG, at most 512 KB. An uploaded icon takes precedence over the logo URL.",
+      "iconUploadedHint": "A custom icon has been uploaded for this favorite.",
+      "iconRemoveButton": "Remove uploaded icon",
+      "iconUrlUnreachable": "The image at this address could not be loaded. The site likely blocks automated requests (for example via a Cloudflare check) or is unreachable. Please upload the icon instead.",
+      "iconTooLarge": "The file is too large – at most 512 KB is allowed.",
+      "iconInvalidType": "Only PNG, JPEG, GIF, WebP, ICO or SVG images are allowed.",
+      "iconUploadFailed": "The icon could not be uploaded."
     },
     "stopwatch": {
       "name": "Stopwatch",