fix(outbounds): test subscriptions in Test All, skip direct/dns

Test All only iterated the editable template outbounds, so subscription
outbounds (the read-only "from subscriptions" table) were never probed in
bulk. They are now queued too, keyed by tag in subscriptionTestStates so
their rows light up live; the template and subscription HTTP lanes run
serially to respect the backend's single-batch lock (TCP runs alongside).

Also stop testing freedom ("direct") and dns outbounds: they aren't
proxies, so an HTTP probe through them only measures the host's own
reachability, not a tunnel. They are now untestable in every mode -- the
per-row button is disabled and Test All skips them -- with a matching
backend guard so a direct API caller can't HTTP-test them either.

frontend/src/pages/xray/outbounds/OutboundCardList.tsx

@@ -110,7 +110,7 @@ export default function OutboundCardList({
                 shape="circle"
                 size="small"
                 loading={isTesting(outboundTestStates, index)}
-                disabled={isUntestable(record, testMode) || isTesting(outboundTestStates, index)}
+                disabled={isUntestable(record) || isTesting(outboundTestStates, index)}
                 icon={<ThunderboltOutlined />}
                 onClick={() => onTest(index, testMode)}
               />

frontend/src/pages/xray/outbounds/SubscriptionOutbounds.tsx

@@ -110,7 +110,7 @@ export default function SubscriptionOutbounds({
           shape="circle"
           size={isMobile ? 'small' : undefined}
           loading={isTesting(subscriptionTestStates, key)}
-          disabled={!record.tag || isUntestable(record, testMode) || isTesting(subscriptionTestStates, key)}
+          disabled={!record.tag || isUntestable(record) || isTesting(subscriptionTestStates, key)}
           icon={<ThunderboltOutlined />}
           onClick={() => onTestSubscription(record as unknown as Record<string, unknown>, testMode)}
         />

frontend/src/pages/xray/outbounds/outbounds-tab-helpers.ts

@@ -31,10 +31,13 @@ export function outboundAddresses(o: OutboundRow): string[] {
   }
 }
 
-export function isUntestable(o: OutboundRow, mode: string): boolean {
+export function isUntestable(o: OutboundRow): boolean {
   if (!o) return true;
   if (o.protocol === Protocols.Blackhole || o.protocol === Protocols.Loopback || o.tag === 'blocked') return true;
-  if (mode === 'tcp' && (o.protocol === Protocols.Freedom || o.protocol === Protocols.DNS)) return true;
+  // freedom ("direct") and dns aren't proxies — a TCP dial has no endpoint and
+  // an HTTP probe would only measure the host's own direct reachability, so
+  // they're untestable in every mode.
+  if (o.protocol === Protocols.Freedom || o.protocol === Protocols.DNS) return true;
   return false;
 }
 

frontend/src/pages/xray/outbounds/useOutboundColumns.tsx

@@ -172,7 +172,7 @@ export function useOutboundColumns({
               type="primary"
               shape="circle"
               loading={isTesting(outboundTestStates, index)}
-              disabled={isUntestable(record, testMode) || isTesting(outboundTestStates, index)}
+              disabled={isUntestable(record) || isTesting(outboundTestStates, index)}
               icon={<ThunderboltOutlined />}
               onClick={() => onTest(index, testMode)}
             />