feat: add translation support

translation/de_de.json5

@@ -0,0 +1,20 @@
+{
+  "dialog.highscore.action": "Gib deinen Namen ein:",
+  "dialog.highscore.title": "Neuer Highscore!",
+  "game.level": "Level: %s",
+  "game.over": "Game over :(",
+  "game.score": "Score: %s",
+  "game.time": "Zeit: %s",
+  "highscores.title": "Highscores:",
+  "menu.exit": "Spiel verlassen",
+  "menu.highscores": "Highscores",
+  "menu.settings": "Einstellungen",
+  "menu.start": "Start",
+  "settings.difficulty": "Schwierigkeit:",
+  "settings.language": "Sprache:",
+  "settings.scale_speed": "Geschwindigkeitszunahme:",
+  "settings.volume.music": "Musik-Lautstärke:",
+  "settings.volume.sound": "Effekt-Lautstärke:",
+  "settings.window_scaling": "Fenster-Skalierung:",
+  "ui.back": "Zurück"
+}