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/services/__init__.py

@@ -0,0 +1,22 @@
+# Backend Services Module
+# Shared services for PDF generation, file processing, and more
+
+# PDFService requires WeasyPrint which needs system libraries (libgobject, etc.)
+# Make import optional for environments without these dependencies (e.g., CI)
+try:
+    from .pdf_service import PDFService
+    _pdf_available = True
+except (ImportError, OSError) as e:
+    PDFService = None  # type: ignore
+    _pdf_available = False
+
+# FileProcessor requires OpenCV which needs libGL.so.1
+# Make import optional for CI environments
+try:
+    from .file_processor import FileProcessor
+    _file_processor_available = True
+except (ImportError, OSError) as e:
+    FileProcessor = None  # type: ignore
+    _file_processor_available = False
+
+__all__ = ["PDFService", "FileProcessor"]