Pest: require district selection + restore B2B auth gate

frontend/src/components/PestAlert.jsx

@@ -122,11 +122,18 @@ export default function PestAlert({ state, crop, district, block }) {
           </div>
         </div>
 
-        <button onClick={fetchPest} disabled={loading || !state}
-          style={{ background: !state ? "#9ca3af" : "#16a34a", color:"#fff", border:"none", borderRadius:"10px", padding:"10px 24px", fontWeight:600, cursor: (!state || loading) ? "not-allowed" : "pointer", opacity: loading ? 0.7 : 1, fontSize:"14px" }}>
+        <button onClick={fetchPest} disabled={loading || !state || !district}
+          style={{ background: (!state || !district) ? "#9ca3af" : "#16a34a", color:"#fff", border:"none", borderRadius:"10px", padding:"10px 24px", fontWeight:600, cursor: (!state || !district || loading) ? "not-allowed" : "pointer", opacity: loading ? 0.7 : 1, fontSize:"14px" }}>
           {loading ? "Analyzing..." : "Get Pest Risk Forecast"}
         </button>
 
+        {/* District required prompt */}
+        {state && !district && (
+          <div style={{ marginTop:"12px", padding:"10px 14px", background:"#fef2f2", borderLeft:"4px solid #dc2626", borderRadius:"0 8px 8px 0", fontSize:"12px", color:"#991b1b", lineHeight:1.5 }}>
+            <strong>Please select a district</strong> — pest risk is driven by local weather conditions.
+          </div>
+        )}
+
         {/* Data level disclaimer */}
         <div style={{ marginTop:"12px", padding:"10px 14px", background:"#fffbeb", borderLeft:"4px solid #f59e0b", borderRadius:"0 8px 8px 0", fontSize:"11px", color:"#78350f", lineHeight:1.5 }}>
           <strong>Note:</strong> Predictions are at <strong>district level</strong> and largely weather-driven —