Restructure: Move final 16 root files into packages (backend-lehrer)

classroom/ (+2): state_engine_api, state_engine_models
vocabulary/ (2): api, db
worksheets/ (2): api, models
services/  (+6): audio, email, translation, claude_vision, ai_processor, story_generator
api/        (4): school, klausur_proxy, progress, user_language

Only main.py + config.py remain at root. 16 shims added.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend-lehrer/ai_processor.py

@@ -1,81 +1,4 @@
-"""
-AI Processor - Legacy Import Wrapper
-
-This file provides backward compatibility for code that imports from ai_processor.
-All functionality has been moved to the ai_processor/ module.
-
-Usage (new):
-    from ai_processor import analyze_scan_structure_with_ai
-
-Usage (legacy, still works):
-    from ai_processor import analyze_scan_structure_with_ai
-"""
-
-# Re-export everything from the new modular structure
-from ai_processor import (
-    # Configuration
-    BASE_DIR,
-    EINGANG_DIR,
-    BEREINIGT_DIR,
-    VISION_API,
-    # Utilities (with legacy aliases)
-    encode_image_to_data_url as _encode_image_to_data_url,
-    dummy_process_scan,
-    # Vision - Scan Analysis
-    analyze_scan_structure_with_ai,
-    describe_scan_with_ai,
-    remove_handwriting_from_scan,
-    build_clean_html_from_analysis,
-    # Generators - Multiple Choice
-    generate_mc_from_analysis,
-    # Generators - Cloze
-    generate_cloze_from_analysis,
-    # Generators - Q&A with Leitner
-    generate_qa_from_analysis,
-    update_leitner_progress,
-    get_next_review_items,
-    # Export - Print Versions
-    generate_print_version_qa,
-    generate_print_version_cloze,
-    generate_print_version_mc,
-    generate_print_version_worksheet,
-    # Visualization - Mindmap
-    generate_mindmap_data,
-    generate_mindmap_html,
-    save_mindmap_for_worksheet,
-)
-
-# Legacy function alias
-from ai_processor import get_openai_api_key as _get_api_key
-
-__all__ = [
-    # Configuration
-    "BASE_DIR",
-    "EINGANG_DIR",
-    "BEREINIGT_DIR",
-    "VISION_API",
-    # Legacy private functions
-    "_get_api_key",
-    "_encode_image_to_data_url",
-    # Vision
-    "analyze_scan_structure_with_ai",
-    "describe_scan_with_ai",
-    "remove_handwriting_from_scan",
-    "build_clean_html_from_analysis",
-    "dummy_process_scan",
-    # Generators
-    "generate_mc_from_analysis",
-    "generate_cloze_from_analysis",
-    "generate_qa_from_analysis",
-    "update_leitner_progress",
-    "get_next_review_items",
-    # Export
-    "generate_print_version_qa",
-    "generate_print_version_cloze",
-    "generate_print_version_mc",
-    "generate_print_version_worksheet",
-    # Visualization
-    "generate_mindmap_data",
-    "generate_mindmap_html",
-    "save_mindmap_for_worksheet",
-]
+# Backward-compat shim -- module moved to services/ai_processor.py
+import importlib as _importlib
+import sys as _sys
+_sys.modules[__name__] = _importlib.import_module("services.ai_processor")