feat(wallpapers): add image crop support and i18n strings

Adds per-image image-crop support with persistent settings.
Rendering adapts to crop mode, zoom and position per image.
Locales the UI strings and notifications; app name updated.

- Cropping workflow with per-image crop state and rendering
- Localizes strings and notifications for en and de
- Introduces set_image_crop command and its permission schema

plugins/permissions/autogenerated/commands/set_image_crop.toml

@@ -0,0 +1,13 @@
+# Automatically generated - DO NOT EDIT!
+
+"$schema" = "../../schemas/schema.json"
+
+[[permission]]
+identifier = "allow-set-image-crop"
+description = "Enables the set_image_crop command without any pre-configured scope."
+commands.allow = ["set_image_crop"]
+
+[[permission]]
+identifier = "deny-set-image-crop"
+description = "Denies the set_image_crop command without any pre-configured scope."
+commands.deny = ["set_image_crop"]