Use emoji icons; :material/ names rendered as literal text

requirements.txt pins no streamlit version and the resolved build does not support
the :material/name: icon syntax, so the alert boxes rendered the raw strings
"trending_up" and "help" next to their messages.

streamlit_app.py

@@ -68,11 +68,11 @@ try:
     from trade_analysis.market_session import banner as _banner, market_status
     _ms = market_status()
     if _ms.get("is_open"):
-        st.success(_banner(_ms), icon=":material/trending_up:")
+        st.success(_banner(_ms), icon="📈")
     elif _ms.get("state") == "unknown":
         st.info(_banner(_ms))
     else:
-        st.warning(_banner(_ms), icon=":material/schedule:")
+        st.warning(_banner(_ms), icon="🕒")
 except Exception as _e:                                      # noqa: BLE001
     st.caption(f"Session status unavailable: {_e}")
 
@@ -165,7 +165,7 @@ if submitted:
     if bits:
         st.caption("  ·  ".join(bits))
     if market.get("warning"):
-        st.warning(market["warning"], icon=":material/warning:")
+        st.warning(market["warning"], icon="⚠️")
 
     # Tiles adapt to the verdict. A "Position Size 0.00" on a HOLD is not information;
     # the margin to the gate that produced the HOLD is.
@@ -194,7 +194,7 @@ if submitted:
         t3.metric("Hold", data.get("expected_hold_time", "—"))
 
     if verdict.get("blocking_reason"):
-        st.info(verdict["blocking_reason"], icon=":material/help:")
+        st.info(verdict["blocking_reason"], icon="💡")
 
     notes = [p.strip() for p in str(data.get("reasoning", "")).split(". ")
              if p.strip().startswith(("Reversal", "Gap", "Overnight"))]