i18n: migrate all German text to English

Enforce the repo convention that committed text is English.
Translates ABOUTME headers, code comments, log/error messages,
shell prompts, and documentation across all files.
CLAUDE.md files remain in German per policy.

defaults/etc/greetd/niri-greeter.kdl

@@ -1,5 +1,5 @@
-// ABOUTME: Niri-Konfiguration fuer den Moongreet Login-Greeter.
-// ABOUTME: Wird von greetd gestartet — minimale Config ohne Keybinds fuer Sicherheit.
+// ABOUTME: Niri configuration for the Moongreet login greeter.
+// ABOUTME: Started by greetd — minimal config without keybinds for security.
 
 input {
     keyboard {
@@ -35,11 +35,11 @@ layout {
     }
 }
 
-// Moongreet starten und niri beenden, sobald moongreet sich schliesst.
-// Retry-Loop stellt sicher, dass niri auch bei fruehen Crashes von moongreet beendet wird.
+// Start moongreet and quit niri once moongreet exits.
+// Retry loop ensures niri shuts down even on early moongreet crashes.
 spawn-sh-at-startup "moongreet; while ! niri msg action quit --skip-confirmation 2>/dev/null; do sleep 0.5; done"
 
-// Greeter-Fenster maximiert darstellen
+// Maximize greeter window
 window-rule {
     open-maximized true
 }
@@ -55,5 +55,5 @@ animations {
 }
 
 binds {
-    // Keine Keybinds — verhindert Zugriff auf Terminals oder andere Aktionen
+    // No keybinds — prevents access to terminals or other actions
 }