Block A: License-Check + Credits-Tracking fuer Enhance und Chat

- Neuer Helper charge_usage_to_tenant() in services/license_service.py:
  UPSERT in token_usage_monthly und Credits-Abzug aus licenses.credits_used.
  Wiederverwendbar fuer alle Claude-Call-Verursacher.
- Orchestrator: Inline-Buchungslogik (35 Zeilen) durch Helper-Aufruf ersetzt.
- routers/incidents.py POST /enhance-description: require_writable_license
  statt get_current_user, db_dependency hinzugefuegt, Credits-Buchung mit
  source="enhance" nach jedem Claude-Call.
- routers/chat.py POST /: analog require_writable_license + Credits-Buchung
  mit source="chat". _call_claude_chat() gibt jetzt zusaetzlich ClaudeUsage
  zurueck.

Abgelaufene/gesperrte Lizenzen koennen damit keine Haiku-Calls mehr ausloesen,
und alle Kosten werden konsistent auf Tenant-Ebene verbucht.

src/routers/chat.py

@@ -12,6 +12,11 @@ from pydantic import BaseModel, Field
 
 from auth import get_current_user
 from config import CLAUDE_PATH, CLAUDE_MODEL_FAST
+from database import db_dependency
+from middleware.license_check import require_writable_license
+from services.license_service import charge_usage_to_tenant
+from agents.claude_client import ClaudeUsage
+import aiosqlite
 
 logger = logging.getLogger("osint.chat")
 
@@ -21,8 +26,8 @@ router = APIRouter(tags=["chat"])
 # Claude CLI Aufruf (Chat-spezifisch, kein JSON-Modus)
 # ---------------------------------------------------------------------------
 
-async def _call_claude_chat(prompt: str) -> tuple[str, int]:
-    """Ruft Claude CLI fuer Chat auf. Gibt (text, duration_ms) zurueck.
+async def _call_claude_chat(prompt: str) -> tuple[str, int, ClaudeUsage]:
+    """Ruft Claude CLI fuer Chat auf. Gibt (text, duration_ms, usage) zurueck.
 
     Anders als call_claude(): kein JSON-Output-Modus, kein append-system-prompt.
     """
@@ -62,21 +67,29 @@ async def _call_claude_chat(prompt: str) -> tuple[str, int]:
     raw = stdout.decode("utf-8", errors="replace").strip()
     duration_ms = 0
     result_text = raw
+    usage = ClaudeUsage()
 
     try:
         data = _json.loads(raw)
         result_text = data.get("result", raw)
         duration_ms = data.get("duration_ms", 0)
-        cost = data.get("total_cost_usd", 0.0)
         u = data.get("usage", {})
+        usage = ClaudeUsage(
+            input_tokens=u.get("input_tokens", 0),
+            output_tokens=u.get("output_tokens", 0),
+            cache_creation_tokens=u.get("cache_creation_input_tokens", 0),
+            cache_read_tokens=u.get("cache_read_input_tokens", 0),
+            cost_usd=data.get("total_cost_usd", 0.0),
+            duration_ms=duration_ms,
+        )
         logger.info(
-            f"Chat Claude: {u.get('input_tokens', 0)} in / {u.get('output_tokens', 0)} out / "
-            f"${cost:.4f} / {duration_ms}ms"
+            f"Chat Claude: {usage.input_tokens} in / {usage.output_tokens} out / "
+            f"${usage.cost_usd:.4f} / {duration_ms}ms"
         )
     except _json.JSONDecodeError:
         logger.warning("Chat Claude CLI Antwort kein JSON, nutze raw output")
 
-    return result_text, duration_ms
+    return result_text, duration_ms, usage
 
 # ---------------------------------------------------------------------------
 # Models
@@ -395,7 +408,8 @@ def _build_prompt(user_message: str, history: list[dict]) -> str:
 @router.post("", response_model=ChatResponse)
 async def chat(
     req: ChatRequest,
-    current_user: dict = Depends(get_current_user),
+    current_user: dict = Depends(require_writable_license),
+    db: aiosqlite.Connection = Depends(db_dependency),
 ):
     """Chat-Nachricht verarbeiten und Antwort generieren."""
     user_id = current_user["id"]
@@ -420,7 +434,7 @@ async def chat(
 
     # Claude CLI aufrufen
     try:
-        result, duration_ms = await _call_claude_chat(prompt)
+        result, duration_ms, usage = await _call_claude_chat(prompt)
     except TimeoutError:
         raise HTTPException(status_code=504, detail="Der Assistent antwortet gerade nicht. Bitte versuche es erneut.")
     except RuntimeError as e:
@@ -430,6 +444,10 @@ async def chat(
         logger.error(f"Chat Claude-Fehler: {e}")
         raise HTTPException(status_code=502, detail="Der Assistent ist voruebergehend nicht erreichbar.")
 
+    # Credits buchen
+    await charge_usage_to_tenant(db, current_user.get("tenant_id"), usage, source="chat")
+    await db.commit()
+
     # Output sanitieren
     reply = _sanitize_output(result)
     if not reply: