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

src/ElementPropertiesApp.jsx

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+// Copyright (C) 2026 Karim Gabriele Varano
+import { useEffect, useState } from 'react'
+import Icon from './components/Icon'
+import { onMessage, notifyReady } from './lib/rhinoBridge'
+import ElementeApp, { PropertiesView } from './ElementeApp.jsx'
+
+// Satellite-Window — zeigt nur die Properties des aktuell selektierten
+// Elements in einem groesseren Fenster. Daten kommen vom ElementeBridge
+// (via STATE-Forward in elemente.py).
+export default function ElementePropertiesApp() {
+  const [state, setState] = useState({
+    elements: [], geschosse: [], selection: null,
+    materials: [], hatchPatterns: [],
+  })
+  useEffect(() => {
+    onMessage('STATE', (s) => setState(prev => ({ ...prev, ...s })))
+    notifyReady()
+  }, [])
+
+  const elements = state.elements || []
+  const selected = elements.find(el => el.id === state.selection)
+
+  return (
+    <div style={{
+      display: 'flex', flexDirection: 'column',
+      height: '100vh', overflow: 'hidden',
+      background: 'var(--bg-base)', color: 'var(--text-primary)',
+      fontFamily: 'var(--font)', fontSize: 11,
+    }}>
+      <div style={{ flex: 1, overflowY: 'auto', overflowX: 'hidden', padding: 12 }}>
+        {selected ? (
+          <PropertiesView
+            selected={selected}
+            geschosse={state.geschosse || []}
+            materials={state.materials || []}
+            hatchPatterns={state.hatchPatterns}
+            fonts={state.fonts || []}
+            oeffStyles={state.oeffStyles || []}
+            wandStyles={state.wandStyles || []}
+            raumStempelStile={state.raumStempelStile || []}
+            stempelStile={state.stempelStile || []}
+          />
+        ) : (
+          <div style={{
+            padding: 60, textAlign: 'center',
+            color: 'var(--text-muted)',
+            display: 'flex', flexDirection: 'column', gap: 10, alignItems: 'center',
+          }}>
+            <Icon name="touch_app" size={32} style={{ color: 'var(--text-muted)', opacity: 0.5 }} />
+            <div>Kein Element selektiert.</div>
+            <div style={{ fontSize: 10 }}>Im Viewport ein Element wählen.</div>
+          </div>
+        )}
+      </div>
+    </div>
+  )
+}