fix: hide Deploy button from Streamlit toolbar

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/gui/app.py

@@ -39,6 +39,12 @@ st.set_page_config(
     layout="wide",
 )
 
+# Hide the Deploy button from the toolbar
+st.markdown(
+    "<style>[data-testid='stAppDeployButton'] {display: none;}</style>",
+    unsafe_allow_html=True,
+)
+
 # ---------------------------------------------------------------------------
 # Session state defaults
 # ---------------------------------------------------------------------------