Keep Gemini secret server-side and fix widget state

app.py

@@ -97,15 +97,20 @@ with st.sidebar:
     )
     st.caption("AUTONOMOUS ANALYSIS WORKSPACE")
     st.markdown("##### Gemini intelligence")
-    default_key = os.getenv("GEMINI_API_KEY", os.getenv("GOOGLE_API_KEY", ""))
-    api_key = st.text_input(
-        "Gemini API key",
-        value=default_key,
+    server_api_key = os.getenv("GEMINI_API_KEY", os.getenv("GOOGLE_API_KEY", ""))
+    user_api_key = st.text_input(
+        "Personal Gemini API key (optional)",
+        value="",
         type="password",
-        help="Masked in the interface and not intentionally written to files or logs.",
+        help="Leave blank to use the secured server-side key. Never stored or logged.",
     )
+    api_key = user_api_key.strip() or server_api_key
     model = st.selectbox("Model", ["gemini-2.5-flash", "gemini-2.5-pro", "gemini-2.0-flash"])
-    st.caption("● AI ready" if api_key else "○ Local analysis mode")
+    st.caption(
+        "● AI ready · secured server key"
+        if server_api_key
+        else ("● AI ready" if api_key else "○ Local analysis mode")
+    )
     st.divider()
     st.markdown("##### Privacy controls")
     metadata_only = st.toggle(