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/ai_processing/__init__.py

@@ -0,0 +1,126 @@
+"""
+AI Processing - Modul für KI-gestützte Arbeitsblatt-Verarbeitung.
+
+Dieses Modul bietet:
+- Bildanalyse mit Vision APIs (OpenAI/Claude)
+- Handschrift-Entfernung aus Scans
+- Generierung von Übungsmaterialien (MC, Lückentext, Q&A)
+- Leitner-System für Spaced Repetition
+- Druck-Versionen für alle Materialtypen
+- Mindmap-Generierung für Lernposter
+
+Verwendung:
+    from ai_processing import analyze_scan_structure_with_ai, generate_mc_from_analysis
+
+    # Oder alle Funktionen:
+    from ai_processing import *
+"""
+
+# Core utilities
+from .core import (
+    BASE_DIR,
+    EINGANG_DIR,
+    BEREINIGT_DIR,
+    get_openai_api_key,
+    get_anthropic_api_key,
+    encode_image_to_data_url,
+    encode_image_to_base64,
+    ensure_directories,
+    dummy_process_scan,
+    get_vision_api,
+)
+
+# Analysis functions
+from .analysis import (
+    describe_scan_with_ai,
+    analyze_scan_structure_with_ai,
+)
+
+# HTML generation
+from .html_generator import (
+    build_clean_html_from_analysis,
+)
+
+# Image processing
+from .image_processor import (
+    remove_handwriting_from_scan,
+)
+
+# Multiple Choice generator
+from .mc_generator import (
+    generate_mc_from_analysis,
+)
+
+# Cloze/Lückentext generator
+from .cloze_generator import (
+    generate_cloze_from_analysis,
+)
+
+# Q&A generator
+from .qa_generator import (
+    generate_qa_from_analysis,
+)
+
+# Leitner system
+from .leitner import (
+    update_leitner_progress,
+    get_next_review_items,
+)
+
+# Print version generators
+from .print_generator import (
+    generate_print_version_qa,
+    generate_print_version_cloze,
+    generate_print_version_mc,
+    generate_print_version_worksheet,
+)
+
+# Mindmap generator
+from .mindmap import (
+    generate_mindmap_data,
+    generate_mindmap_html,
+    save_mindmap_for_worksheet,
+)
+
+# Legacy aliases for backwards compatibility
+_get_api_key = get_openai_api_key
+_encode_image_to_data_url = encode_image_to_data_url
+
+__all__ = [
+    # Core
+    "BASE_DIR",
+    "EINGANG_DIR",
+    "BEREINIGT_DIR",
+    "get_openai_api_key",
+    "get_anthropic_api_key",
+    "encode_image_to_data_url",
+    "encode_image_to_base64",
+    "ensure_directories",
+    "dummy_process_scan",
+    "get_vision_api",
+    # Analysis
+    "describe_scan_with_ai",
+    "analyze_scan_structure_with_ai",
+    # HTML
+    "build_clean_html_from_analysis",
+    # Image
+    "remove_handwriting_from_scan",
+    # MC
+    "generate_mc_from_analysis",
+    # Cloze
+    "generate_cloze_from_analysis",
+    # Q&A
+    "generate_qa_from_analysis",
+    # Leitner
+    "update_leitner_progress",
+    "get_next_review_items",
+    # Print
+    "generate_print_version_qa",
+    "generate_print_version_cloze",
+    "generate_print_version_mc",
+    "generate_print_version_worksheet",
+    # Mindmap
+    "generate_mindmap_data",
+    "generate_mindmap_html",
+    "save_mindmap_for_worksheet",
+]