i18n DE/EN + DossierSettings panel + English file renames

i18n:
- src/i18n/de.json + en.json: 200+ keys covering all main panels
- src/i18n/index.js: t(key, vars) reads window.DOSSIER_LANG
- panel_base.py: injects window.DOSSIER_LANG from dossier_settings.json
- EbenenManager, GeschossManager, AusschnitteApp, LayoutsApp: all
  context menus and main labels use t()

DossierSettings panel:
- DossierSettingsApp.jsx: language toggle (DE/EN pill) + launcher status
- toolbar.py: OPEN_SETTINGS opens new Rhino-hosted satellite window,
  SAVE_LANG writes lang to dossier_settings.json + reloads all panels

File renames (JSX → English):
- ZeichnungsebenenApp → DrawingLevelsApp
- GeschossManager/Dialog/Settings → Floor*
- AusschnitteApp/Settings → Viewports*
- EbenenManager/Settings → Layer*
- GestaltungApp → StylesApp, OberleisteApp → ToolbarApp
- WerkzeugeApp → ToolsApp, DimensionenApp → DimensionsApp
- MassstabApp → ScaleApp, KameraApp → CameraApp
- MasseSettingsApp → UnitsSettingsApp
- ConfirmDeleteEbene → ConfirmDeleteLayer
- AusschnittLayerDialog → ViewportLayerDialog

Python module renames:
- rhinopanel.py → layers_panel.py
- oberleiste.py → toolbar.py
- gestaltung.py → styles.py
- werkzeuge.py → tools.py
- dimensionen.py → dimensions.py
- startup.py _MODULE_TO_PY updated, all cross-imports fixed

rhino/ausschnitte.py

@@ -556,7 +556,7 @@ class AusschnittBridge(panel_base.BaseBridge):
         kombi = (snap.get("layerCombination") or "").strip()
         if kombi:
             try:
-                import rhinopanel
+                import layers_panel as rhinopanel
                 rhinopanel.apply_layer_preset_by_name(doc, kombi)
             except Exception as ex:
                 print("[AUSSCHNITTE] kombi-apply '{}':".format(kombi), ex)
@@ -565,7 +565,7 @@ class AusschnittBridge(panel_base.BaseBridge):
             _apply_layers_global(doc, snap.get("layers", []))
             # Eigene Sichtbarkeit → active_comb_name clearen
             try:
-                import rhinopanel
+                import layers_panel as rhinopanel
                 rhinopanel.set_active_comb_name(doc, None)
                 rhinopanel._notify_oberleiste_combs()
             except Exception: pass
@@ -785,7 +785,7 @@ class AusschnittBridge(panel_base.BaseBridge):
             # Listen fuer Dropdowns
             display_modes = []
             try:
-                import oberleiste
+                import toolbar as oberleiste
                 display_modes = oberleiste._list_display_modes()
             except Exception as ex:
                 print("[AUSSCHNITTE] display_modes:", ex)
@@ -797,7 +797,7 @@ class AusschnittBridge(panel_base.BaseBridge):
                 print("[AUSSCHNITTE] overrides_presets:", ex)
             layer_kombis = []
             try:
-                import rhinopanel
+                import layers_panel as rhinopanel
                 layer_kombis = rhinopanel.list_layer_preset_names(d)
             except Exception as ex:
                 print("[AUSSCHNITTE] layer_kombis:", ex)