feat: include ongoing timer in balance calculation

The balance now accounts for any active timer whose project belongs to
the tracked client. computeBalance() fetches the user's OngoingTimer,
computes its elapsed seconds, and adds them to the matching period's
tracked seconds before running the balance formula — so both
currentPeriodTrackedSeconds and totalBalanceSeconds reflect the live
timer without requiring a schema change.

On the frontend, useClientTargets polls every 30 s while a timer is
running, and a pulsing green dot is shown next to the balance figure on
the Dashboard and Clients pages to signal the live contribution.

frontend/src/hooks/useClientTargets.ts

@@ -1,5 +1,6 @@
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import { clientTargetsApi } from '@/api/clientTargets';
+import { useTimer } from '@/contexts/TimerContext';
 import type {
   CreateClientTargetInput,
   UpdateClientTargetInput,
@@ -8,10 +9,13 @@ import type {
 
 export function useClientTargets() {
   const queryClient = useQueryClient();
+  const { ongoingTimer } = useTimer();
 
   const { data: targets, isLoading, error } = useQuery({
     queryKey: ['clientTargets'],
     queryFn: clientTargetsApi.getAll,
+    // Poll every 30 s while a timer is running so the balance stays current
+    refetchInterval: ongoingTimer ? 30_000 : false,
   });
 
   const createTarget = useMutation({

frontend/src/pages/ClientsPage.tsx

@@ -316,6 +316,12 @@ function ClientTargetPanel({
             <span className="font-medium">{target!.targetHours}h</span>/{periodLabel}
           </span>
           <span className={`text-xs font-semibold ${balance.color}`}>{balance.text}</span>
+          {target!.hasOngoingTimer && (
+            <span
+              className="inline-block h-2 w-2 rounded-full bg-green-500 animate-pulse"
+              title="Timer running — balance updates every 30 s"
+            />
+          )}
         </div>
         <div className="flex items-center gap-1">
           <button

frontend/src/pages/DashboardPage.tsx

@@ -132,19 +132,27 @@ export function DashboardPage() {
                       </p>
                   </div>
                   <div className="text-right">
-                    <p
-                      className={`text-sm font-bold ${
-                        isEven
-                          ? 'text-gray-500'
-                          : isOver
-                          ? 'text-green-600'
-                          : 'text-red-600'
-                      }`}
-                    >
-                      {isEven
-                        ? '±0'
-                        : (isOver ? '+' : '−') + formatDurationHoursMinutes(absBalance)}
-                    </p>
+                    <div className="flex items-center justify-end gap-1.5">
+                      {target.hasOngoingTimer && (
+                        <span
+                          className="inline-block h-2 w-2 rounded-full bg-green-500 animate-pulse"
+                          title="Timer running — balance updates every 30 s"
+                        />
+                      )}
+                      <p
+                        className={`text-sm font-bold ${
+                          isEven
+                            ? 'text-gray-500'
+                            : isOver
+                            ? 'text-green-600'
+                            : 'text-red-600'
+                        }`}
+                      >
+                        {isEven
+                          ? '±0'
+                          : (isOver ? '+' : '−') + formatDurationHoursMinutes(absBalance)}
+                      </p>
+                    </div>
                     <p className="text-xs text-gray-400">running balance</p>
                   </div>
                 </div>

frontend/src/types/index.ts

@@ -186,6 +186,8 @@ export interface ClientTargetWithBalance {
   currentPeriodTrackedSeconds: number;
   currentPeriodTargetSeconds: number;
   periods: PeriodBalance[];
+  /** True when an active timer for a project belonging to this client is running. */
+  hasOngoingTimer: boolean;
 }
 
 export interface CreateClientTargetInput {