Multilanguage: Deutsch / English, umschaltbar in Einstellungen

- i18n.js: Übersetzungsmodul mit t(), setLang(), applyLang() + vollst. DE/EN Wörterbuch
- Backend: language-Feld in UserSettings, Migration, Settings-API
- calendar.js: alle deutschen Strings auf t()-Aufrufe umgestellt, setLang() beim Start
- app.js, api.js, color-picker.js, views/*.js: alle UI-Strings übersetzt
- Sprach-Dropdown in Einstellungen > Darstellung, data-i18n-Attribute in index.html

backend/main.py

@@ -58,6 +58,11 @@ def _migrate():
             conn.commit()
         except Exception:
             pass
+        try:
+            conn.execute(text("ALTER TABLE user_settings ADD COLUMN language VARCHAR(5) DEFAULT 'de'"))
+            conn.commit()
+        except Exception:
+            pass
 
 _migrate()
 

backend/models.py

@@ -78,6 +78,7 @@ class UserSettings(Base):
     text_contrast = Column(Integer, default=3)
     line_contrast = Column(Integer, default=3)
     hour_height = Column(Integer, default=60)
+    language = Column(String(5), default="de")
 
     user = relationship("User", back_populates="settings")
 

backend/routers/settings_router.py

@@ -21,6 +21,7 @@ class SettingsUpdate(BaseModel):
     text_contrast: Optional[int] = None
     line_contrast: Optional[int] = None
     hour_height: Optional[int] = None
+    language: Optional[str] = None
 
 
 def _settings_dict(s: models.UserSettings) -> dict:
@@ -34,6 +35,7 @@ def _settings_dict(s: models.UserSettings) -> dict:
         "text_contrast": s.text_contrast or 3,
         "line_contrast": s.line_contrast or 3,
         "hour_height": s.hour_height or 60,
+        "language": s.language or "de",
     }