refactor(branding): rename project to LockScreenWallpaper across repo

Standardize branding by renaming Wechselbild to LockScreenWallpaper.
This updates UI strings, configs, and plugin metadata for consistency.

- Rename branding across UI, docs, and config in the repo
- Update Android UI strings and notification titles to LockScreenWallpaper

src-tauri/Cargo.toml

@@ -1,12 +1,12 @@
 [package]
-name = "wechselbild"
+name = "lockscreenwallpaper"
 version = "0.1.0"
 description = "Unbegrenzter Sperrbildschirm-Wechsel für Android"
-authors = ["Wechselbild"]
+authors = ["LockScreenWallpaper"]
 edition = "2021"
 
 [lib]
-name = "wechselbild_lib"
+name = "lockscreenwallpaper_lib"
 crate-type = ["staticlib", "cdylib", "rlib"]
 
 [build-dependencies]