Fix UI: Dynamic metric deltas

Dockerfile

@@ -1,7 +1,7 @@
 FROM python:3.10-slim-bullseye
 
 WORKDIR /app
-ENV CACHE_BUST=20251216_1520
+ENV CACHE_BUST=20251216_1527
 
 # Install system dependencies
 RUN apt-get update && apt-get install -y \

mi_platform/ui/dashboard.py

@@ -136,14 +136,14 @@ with tab2:
     feature_cols = [c for c in df_process.columns if c not in ['Timestamp', 'Time', 'Pass/Fail']][:4]
     
     col1, col2, col3, col4 = st.columns(4)
-    with col1:
-        st.metric("Chamber Pressure", f"{df_window[feature_cols[0]].iloc[-1]:.2f}", delta="0.05")
-    with col2:
-        st.metric("Gas Flow Rate", f"{df_window[feature_cols[1]].iloc[-1]:.2f}", delta="-0.12")
-    with col3:
-        st.metric("RF Power", f"{df_window[feature_cols[2]].iloc[-1]:.2f}", delta="0.01")
-    with col4:
-        st.metric("Wafer Temp", f"{df_window[feature_cols[3]].iloc[-1]:.2f}", delta="1.2")
+    for i, col_name in enumerate(["Chamber Pressure", "Gas Flow Rate", "RF Power", "Wafer Temp"]):
+        col = feature_cols[i]
+        curr = df_window[col].iloc[-1]
+        prev = df_window[col].iloc[-2] if len(df_window) > 1 else curr
+        delta = curr - prev
+        
+        with [col1, col2, col3, col4][i]:
+            st.metric(col_name, f"{curr:.2f}", delta=f"{delta:.2f}")
         
     # Charts
     st.subheader("Sensor Trends")