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/llm_gateway/routes/health.py

@@ -0,0 +1,127 @@
+"""
+Health Check Route.
+"""
+
+import logging
+from datetime import datetime
+from fastapi import APIRouter
+from pydantic import BaseModel
+
+from ..config import get_config
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(tags=["Health"])
+
+
+class ComponentStatus(BaseModel):
+    """Status einer Komponente."""
+    name: str
+    status: str  # healthy, degraded, unhealthy
+    message: str = ""
+
+
+class HealthResponse(BaseModel):
+    """Health Check Response."""
+    status: str  # ok, degraded, error
+    ts: str
+    version: str
+    components: list[ComponentStatus]
+
+
+@router.get("/health", response_model=HealthResponse)
+async def health_check():
+    """
+    Health Check Endpoint.
+
+    Prüft den Status aller Komponenten:
+    - Gateway selbst
+    - LLM Backend Erreichbarkeit
+    - Datenbank (wenn konfiguriert)
+    """
+    config = get_config()
+    components = []
+    overall_status = "ok"
+
+    # Gateway selbst
+    components.append(ComponentStatus(
+        name="gateway",
+        status="healthy",
+        message="Gateway is running",
+    ))
+
+    # Ollama Backend
+    if config.ollama and config.ollama.enabled:
+        try:
+            import httpx
+            async with httpx.AsyncClient(timeout=5.0) as client:
+                response = await client.get(f"{config.ollama.base_url}/api/tags")
+                if response.status_code == 200:
+                    components.append(ComponentStatus(
+                        name="ollama",
+                        status="healthy",
+                        message="Ollama is reachable",
+                    ))
+                else:
+                    components.append(ComponentStatus(
+                        name="ollama",
+                        status="degraded",
+                        message=f"Ollama returned status {response.status_code}",
+                    ))
+                    overall_status = "degraded"
+        except Exception as e:
+            components.append(ComponentStatus(
+                name="ollama",
+                status="unhealthy",
+                message=f"Cannot reach Ollama: {str(e)}",
+            ))
+            # Nicht critical wenn andere Backends verfügbar
+            if not (config.vllm and config.vllm.enabled) and not (config.anthropic and config.anthropic.enabled):
+                overall_status = "error"
+
+    # vLLM Backend
+    if config.vllm and config.vllm.enabled:
+        try:
+            import httpx
+            headers = {}
+            if config.vllm.api_key:
+                headers["Authorization"] = f"Bearer {config.vllm.api_key}"
+            async with httpx.AsyncClient(timeout=5.0) as client:
+                response = await client.get(
+                    f"{config.vllm.base_url}/v1/models",
+                    headers=headers,
+                )
+                if response.status_code == 200:
+                    components.append(ComponentStatus(
+                        name="vllm",
+                        status="healthy",
+                        message="vLLM is reachable",
+                    ))
+                else:
+                    components.append(ComponentStatus(
+                        name="vllm",
+                        status="degraded",
+                        message=f"vLLM returned status {response.status_code}",
+                    ))
+                    overall_status = "degraded"
+        except Exception as e:
+            components.append(ComponentStatus(
+                name="vllm",
+                status="unhealthy",
+                message=f"Cannot reach vLLM: {str(e)}",
+            ))
+
+    # Anthropic Backend
+    if config.anthropic and config.anthropic.enabled:
+        components.append(ComponentStatus(
+            name="anthropic",
+            status="healthy",
+            message="Anthropic API configured (not checked)",
+        ))
+
+    return HealthResponse(
+        status=overall_status,
+        ts=datetime.utcnow().isoformat() + "Z",
+        version="0.1.0",
+        components=components,
+    )