fix: Restore all files lost during destructive rebase

A previous `git pull --rebase origin main` dropped 177 local commits,
losing 3400+ files across admin-v2, backend, studio-v2, website,
klausur-service, and many other services. The partial restore attempt
(660295e2) only recovered some files.

This commit restores all missing files from pre-rebase ref 98933f5e
while preserving post-rebase additions (night-scheduler, night-mode UI,
NightModeWidget dashboard integration).

Restored features include:
- AI Module Sidebar (FAB), OCR Labeling, OCR Compare
- GPU Dashboard, RAG Pipeline, Magic Help
- Klausur-Korrektur (8 files), Abitur-Archiv (5+ files)
- Companion, Zeugnisse-Crawler, Screen Flow
- Full backend, studio-v2, website, klausur-service
- All compliance SDKs, agent-core, voice-service
- CI/CD configs, documentation, scripts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/tools/migrate_frontend_ui.py

@@ -0,0 +1,73 @@
+import re
+from pathlib import Path
+
+
+def extract_app_ui_body(source_text: str) -> str:
+    """
+    Extrahiert den HTML-Block aus der alten app_ui()-Funktion.
+    """
+    match = re.search(r"def app_ui[^(]*\([^)]*\):\s*\n(\s*)return \"\"\"", source_text)
+    if not match:
+        raise RuntimeError("Konnte def app_ui() mit return \"\"\" nicht finden.")
+
+    indent = match.group(1)
+    start = match.end()  # direkt hinter return \"\"\" beginnt der HTML-Code
+    close_pattern = "\n" + indent + '"""'
+    end = source_text.find(close_pattern, start)
+
+    if end == -1:
+        raise RuntimeError("Konnte schließende \"\"\" nicht finden.")
+
+    body = source_text[start:end]
+    return body
+
+
+def build_frontend_studio_file(html_body: str) -> str:
+    """
+    Baut die vollständige Datei studio.py mit APIRouter + HTML-Block.
+    """
+    header = (
+        "from fastapi import APIRouter\n"
+        "from fastapi.responses import HTMLResponse\n\n"
+        "router = APIRouter()\n\n\n"
+        "@router.get(\"/app\", response_class=HTMLResponse)\n"
+        "def app_ui():\n"
+        "    return \"\"\""
+    )
+
+    footer = "\n    \"\"\"\n"
+    return header + html_body + footer
+
+
+def main():
+    backend_dir = Path(__file__).parent
+
+    # 1) Sicherungsdatei bevorzugt
+    backup_path = backend_dir / "frontend_app_backup.py"
+    if backup_path.exists():
+        source_path = backup_path
+        print(f"Verwende Sicherungsdatei: {source_path}")
+    else:
+        # 2) Fallback auf frontend/app.py
+        candidate = backend_dir / "frontend" / "app.py"
+        if not candidate.exists():
+            raise RuntimeError(
+                "Keine Quelle gefunden: frontend_app_backup.py oder frontend/app.py fehlen."
+            )
+        source_path = candidate
+        print(f"Verwende Datei: {source_path}")
+
+    source_text = source_path.read_text(encoding="utf-8")
+    html_body = extract_app_ui_body(source_text)
+
+    studio_text = build_frontend_studio_file(html_body)
+
+    studio_path = backend_dir / "frontend" / "studio.py"
+    studio_path.write_text(studio_text, encoding="utf-8")
+
+    print(f"frontend/studio.py erfolgreich erzeugt: {studio_path}")
+
+
+if __name__ == "__main__":
+    main()
+