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>

klausur-service/backend/pdf_extraction.py

@@ -0,0 +1,164 @@
+"""
+PDF Extraction Module
+
+NOTE: This module delegates ML-heavy operations to the embedding-service via HTTP.
+
+Provides enhanced PDF text extraction using multiple backends (in embedding-service):
+1. Unstructured.io - Best for complex layouts, tables, headers (Apache 2.0)
+2. pypdf - Modern, BSD-licensed PDF library (recommended default)
+
+License Compliance:
+- Default backends (unstructured, pypdf) are BSD/Apache licensed
+"""
+
+import os
+import logging
+from typing import Dict, List, Optional
+
+logger = logging.getLogger(__name__)
+
+# Configuration (for backward compatibility - actual config in embedding-service)
+EMBEDDING_SERVICE_URL = os.getenv("EMBEDDING_SERVICE_URL", "http://embedding-service:8087")
+PDF_BACKEND = os.getenv("PDF_EXTRACTION_BACKEND", "auto")
+
+
+class PDFExtractionError(Exception):
+    """Error during PDF extraction."""
+    pass
+
+
+class PDFExtractionResult:
+    """Result of PDF extraction with metadata."""
+
+    def __init__(
+        self,
+        text: str,
+        backend_used: str,
+        pages: int = 0,
+        elements: Optional[List[Dict]] = None,
+        tables: Optional[List[Dict]] = None,
+        metadata: Optional[Dict] = None,
+    ):
+        self.text = text
+        self.backend_used = backend_used
+        self.pages = pages
+        self.elements = elements or []
+        self.tables = tables or []
+        self.metadata = metadata or {}
+
+    def to_dict(self) -> Dict:
+        return {
+            "text": self.text,
+            "backend_used": self.backend_used,
+            "pages": self.pages,
+            "element_count": len(self.elements),
+            "table_count": len(self.tables),
+            "metadata": self.metadata,
+        }
+
+
+def _detect_available_backends() -> List[str]:
+    """Get available backends from embedding-service."""
+    import httpx
+
+    try:
+        with httpx.Client(timeout=5.0) as client:
+            response = client.get(f"{EMBEDDING_SERVICE_URL}/models")
+            if response.status_code == 200:
+                data = response.json()
+                return data.get("available_pdf_backends", ["pypdf"])
+    except Exception as e:
+        logger.warning(f"Could not reach embedding-service: {e}")
+
+    return []
+
+
+def extract_text_from_pdf_enhanced(
+    pdf_content: bytes,
+    backend: str = PDF_BACKEND,
+    fallback: bool = True,
+) -> PDFExtractionResult:
+    """
+    Extract text from PDF using embedding-service.
+
+    Args:
+        pdf_content: PDF file content as bytes
+        backend: Preferred backend (auto, unstructured, pypdf)
+        fallback: If True, try other backends if preferred fails
+
+    Returns:
+        PDFExtractionResult with extracted text and metadata
+    """
+    import httpx
+
+    try:
+        with httpx.Client(timeout=120.0) as client:
+            response = client.post(
+                f"{EMBEDDING_SERVICE_URL}/extract-pdf",
+                content=pdf_content,
+                headers={"Content-Type": "application/octet-stream"}
+            )
+            response.raise_for_status()
+            data = response.json()
+
+            return PDFExtractionResult(
+                text=data.get("text", ""),
+                backend_used=data.get("backend_used", "unknown"),
+                pages=data.get("pages", 0),
+                tables=[{"count": data.get("table_count", 0)}] if data.get("table_count", 0) > 0 else [],
+                metadata={"embedding_service": True}
+            )
+    except httpx.TimeoutException:
+        raise PDFExtractionError("PDF extraction timeout")
+    except httpx.HTTPStatusError as e:
+        raise PDFExtractionError(f"PDF extraction error: {e.response.status_code}")
+    except Exception as e:
+        raise PDFExtractionError(f"Failed to extract PDF: {str(e)}")
+
+
+def extract_text_from_pdf(pdf_content: bytes) -> str:
+    """
+    Extract text from PDF (simple interface).
+
+    This is a drop-in replacement for the original function
+    that uses the embedding-service internally.
+    """
+    result = extract_text_from_pdf_enhanced(pdf_content)
+    return result.text
+
+
+def get_pdf_extraction_info() -> dict:
+    """Get information about PDF extraction configuration."""
+    import httpx
+
+    try:
+        with httpx.Client(timeout=5.0) as client:
+            response = client.get(f"{EMBEDDING_SERVICE_URL}/models")
+            if response.status_code == 200:
+                data = response.json()
+                available = data.get("available_pdf_backends", [])
+                return {
+                    "configured_backend": data.get("pdf_backend", PDF_BACKEND),
+                    "available_backends": available,
+                    "recommended": "unstructured" if "unstructured" in available else "pypdf",
+                    "backend_licenses": {
+                        "unstructured": "Apache-2.0",
+                        "pypdf": "BSD-3-Clause",
+                    },
+                    "commercial_safe_backends": available,
+                    "embedding_service_url": EMBEDDING_SERVICE_URL,
+                    "embedding_service_available": True,
+                }
+    except Exception as e:
+        logger.warning(f"Could not reach embedding-service: {e}")
+
+    # Fallback when embedding-service is not available
+    return {
+        "configured_backend": PDF_BACKEND,
+        "available_backends": [],
+        "recommended": None,
+        "backend_licenses": {},
+        "commercial_safe_backends": [],
+        "embedding_service_url": EMBEDDING_SERVICE_URL,
+        "embedding_service_available": False,
+    }