feat: auto-calculate deadlines on proceeding type selection (no click needed)

frontend/src/components/deadlines/DeadlineCalculator.tsx

@@ -51,13 +51,28 @@ export function DeadlineCalculator() {
     }) => api.post<CalculateResponse>("/deadlines/calculate", params),
   });
 
+  // Auto-calculate when proceeding type changes (using current trigger date)
+  function doCalculate(type: string, date: string) {
+    if (!type || !date) return;
+    calculateMutation.mutate({
+      proceeding_type: type,
+      trigger_event_date: date,
+    });
+  }
+
+  function handleProceedingChange(newType: string) {
+    setProceedingType(newType);
+    doCalculate(newType, triggerDate);
+  }
+
+  function handleDateChange(newDate: string) {
+    setTriggerDate(newDate);
+    if (proceedingType) doCalculate(proceedingType, newDate);
+  }
+
   function handleCalculate(e: React.FormEvent) {
     e.preventDefault();
-    if (!proceedingType || !triggerDate) return;
-    calculateMutation.mutate({
-      proceeding_type: proceedingType,
-      trigger_event_date: triggerDate,
-    });
+    doCalculate(proceedingType, triggerDate);
   }
 
   const results = calculateMutation.data;
@@ -80,7 +95,7 @@ export function DeadlineCalculator() {
             </label>
             <select
               value={proceedingType}
-              onChange={(e) => setProceedingType(e.target.value)}
+              onChange={(e) => handleProceedingChange(e.target.value)}
               disabled={typesLoading}
               className={inputClass}
             >
@@ -131,7 +146,7 @@ export function DeadlineCalculator() {
             <input
               type="date"
               value={triggerDate}
-              onChange={(e) => setTriggerDate(e.target.value)}
+              onChange={(e) => handleDateChange(e.target.value)}
               className={inputClass}
             />
           </div>