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_processor/config.py

@@ -0,0 +1,43 @@
+"""
+AI Processor - Configuration
+
+API keys, constants, and directory paths.
+"""
+
+from pathlib import Path
+import os
+import logging
+
+logger = logging.getLogger(__name__)
+
+# Directory Configuration
+BASE_DIR = Path.home() / "Arbeitsblaetter"
+EINGANG_DIR = BASE_DIR / "Eingang"
+BEREINIGT_DIR = BASE_DIR / "Bereinigt"
+
+# Vision API Configuration
+# Set VISION_API environment variable to "openai" or "claude" (default: claude)
+VISION_API = os.getenv("VISION_API", "claude").lower()
+
+
+def get_openai_api_key() -> str:
+    """Get OpenAI API key from environment."""
+    api_key = os.getenv("OPENAI_API_KEY")
+    if not api_key:
+        raise RuntimeError("OPENAI_API_KEY ist nicht gesetzt. Bitte API-Schluessel als Umgebungsvariable setzen.")
+    return api_key
+
+
+def get_anthropic_api_key() -> str:
+    """Get Anthropic API key from environment."""
+    api_key = os.getenv("ANTHROPIC_API_KEY")
+    if not api_key:
+        raise RuntimeError("ANTHROPIC_API_KEY ist nicht gesetzt.")
+    return api_key
+
+
+# Ensure directories exist
+def ensure_directories():
+    """Create directories if they don't exist."""
+    EINGANG_DIR.mkdir(parents=True, exist_ok=True)
+    BEREINIGT_DIR.mkdir(parents=True, exist_ok=True)