Add Windows download button on quickstart page

Serve the bundled OpenMS-App.zip (downloaded into /app by the Dockerfile)
as a cached, server-wide resource via st.download_button on the
DDA-LFQ quickstart page. The button is hidden when the asset is not
present (e.g. local dev runs without the bundled build).

Author: claude

content/quickstart.py

@@ -5,13 +5,35 @@
 for getting started with the analysis pipeline.
 """
 
+from pathlib import Path
+
 import streamlit as st
 from src.common.common import page_setup
 
+WINDOWS_APP_PATH = Path("/app/OpenMS-App.zip")
+
+
+@st.cache_resource
+def load_windows_app_bytes() -> bytes | None:
+    if WINDOWS_APP_PATH.exists():
+        return WINDOWS_APP_PATH.read_bytes()
+    return None
+
+
 page_setup(page="main")
 
 st.markdown("# DDA Label-Free Quantification")
 
+windows_app_bytes = load_windows_app_bytes()
+if windows_app_bytes is not None:
+    st.download_button(
+        label="Download for Windows",
+        data=windows_app_bytes,
+        file_name="OpenMS-App.zip",
+        mime="application/zip",
+        icon=":material/download:",
+    )
+
 st.markdown(
     """
 This application provides a complete **Data-Dependent Acquisition (DDA) Label-Free Quantification**