fix: remove broken capital controls, reset now queries broker for real balance

- Removed PUT /api/trading/capital (set capital) — only touched in-memory state
- Removed POST /api/trading/capital/adjust (add/withdraw) — same problem
- Reset endpoint now: liquidates Alpaca positions, cancels orders, clears DB,
  then queries Alpaca for real portfolio_value to set engine capital
- Frontend: replaced CapitalCard with simple ResetCard (one button)
- Removed useSetTradingCapital and useAdjustCapital hooks

frontend/src/api/hooks.ts

@@ -426,15 +426,6 @@ export function useSetTradingMode() {
   });
 }
 
-export function useSetTradingCapital() {
-  const qc = useQueryClient();
-  return useMutation({
-    mutationFn: (initial_capital: number) =>
-      apiPut<{ initial_capital: number; active_pool: number; reserve_pool: number }>('trading', '/api/trading/capital', { initial_capital }),
-    onSuccess: () => qc.invalidateQueries({ queryKey: ['trading-config'] }),
-  });
-}
-
 export function usePendingApprovals() {
   return useGet<Approval[]>(['pending-approvals'], 'query', '/api/admin/trading/approvals');
 }

frontend/src/api/tradingHooks.ts

@@ -309,12 +309,13 @@ export function useBacktestLaunch() {
   });
 }
 
-/** Full paper trading reset: clears all positions, orders, decisions, and resets capital. */
+/** Full paper trading reset: liquidates broker positions, cancels orders,
+ *  clears all local trading state, and syncs capital from the broker. */
 export function useResetPaperTrading() {
   const qc = useQueryClient();
   return useMutation({
-    mutationFn: (initial_capital: number) =>
-      apiPost<{ reset: boolean; initial_capital: number; active_pool: number; reserve_pool: number }>(
+    mutationFn: (initial_capital: number = 0) =>
+      apiPost<{ reset: boolean; initial_capital: number; active_pool: number; reserve_pool: number; broker: Record<string, number> }>(
         'trading', '/api/trading/reset', { initial_capital },
       ),
     onSuccess: () => {
@@ -326,21 +327,6 @@ export function useResetPaperTrading() {
   });
 }
 
-/** Add or subtract capital from the active pool without resetting anything else. */
-export function useAdjustCapital() {
-  const qc = useQueryClient();
-  return useMutation({
-    mutationFn: (amount: number) =>
-      apiPost<{ adjusted: number; active_pool: number; reserve_pool: number; total_value: number }>(
-        'trading', '/api/trading/capital/adjust', { amount },
-      ),
-    onSuccess: () => {
-      qc.invalidateQueries({ queryKey: ['trading-status'] });
-      qc.invalidateQueries({ queryKey: ['trading-metrics'] });
-    },
-  });
-}
-
 /** Update notification preferences. */
 export function useUpdateNotificationConfig() {
   const qc = useQueryClient();