feat(CG4-credits): GET /billing/credits + docstring CG4 + GOOGLE_CREDIT_TOTAL_USD støtte

main.py

@@ -13,6 +13,8 @@ CG5-onboard: GET /onboard + POST /onboard/complete — klient-onboarding wizard.
 DOCS: GET /docs/{path} — proxy til privat GitHub-repo via ADC/PAT.
 OQ-29: GET /notify/channels — list delivery-kanaler per gcp_project.
 OQ-31: GET /opax/build-status — ekte Cloud Build-status.
+CG4-credits: GET /billing/credits — kreditt-saldo, burn rate og tom-dato.
+             Krever GOOGLE_CREDIT_TOTAL_USD i Cloud Run env for runway-beregning.
 """
 
 import os
@@ -653,6 +655,37 @@ async def authenticated_billing_anomalies(request: Request):
 app.add_api_route("/billing/anomalies", endpoint=require_auth(authenticated_billing_anomalies), methods=["GET"])
 
 
+# ── CG4-credits: GET /billing/credits ────────────────────────────────────────
+async def authenticated_billing_credits(request: Request, days: int = 90):
+    """
+    CG4-credits — Kreditt-saldo, burn rate og estimert tom-dato.
+
+    Query params:
+      days (int, default 90): Analyseperiode i dager.
+
+    Krever env-var GOOGLE_CREDIT_TOTAL_USD satt i Cloud Run for
+    nøyaktig runway-beregning. Uten denne vises kun burn rate.
+
+    Eksempel-respons:
+      {
+        "credits_used_total_usd": 994.66,
+        "credits_remaining_usd": 305.34,
+        "credit_total_usd": 1300.0,
+        "daily_credit_burn_usd": 14.2,
+        "credit_runway_days": 21,
+        "credit_exhaustion_date": "2026-07-04",
+        "warning": "⚠️ Kreditter estimert tom om 21 dager (2026-07-04).",
+        ...
+      }
+    """
+    try:
+        return JSONResponse(BillingAgent().get_credits_status(days=days))
+    except Exception as exc:
+        return JSONResponse(status_code=500, content={"error": str(exc)})
+
+app.add_api_route("/billing/credits", endpoint=require_auth(authenticated_billing_credits), methods=["GET"])
+
+
 @app.get("/billing-dashboard")
 def billing_dashboard_view(request: Request):
     return RedirectResponse(url='/static/billing-dashboard.html')