Update app.py

app.py

@@ -139,7 +139,7 @@ def carbon_trend():
         plt.title("Carbon Intensity Trend")
         plt.legend()
         plt.tight_layout()
-        plt.savefig("carbon_trend_plot.png")
+        plt.savefig("/tmp/carbon_trend_plot.png")
 
         return {
             "trend_slope": round(slope, 4),
@@ -153,4 +153,4 @@ def carbon_trend():
 # Optional: Return trend plot image
 @app.get("/carbon-trend/plot")
 def get_trend_plot():
-    return FileResponse("carbon_trend_plot.png", media_type="image/png")
+    return FileResponse("/tmp/carbon_trend_plot.png", media_type="image/png")