feat(mtproto): per-client ad-tags, management-API auth, and record secret sync

Catch the panel up to the mtg-multi README (v1.14.0):

- Each client can now carry its own 32-hex advertising tag overriding the
  inbound-level one. The tag lives on the client (settings JSON is the
  source of truth, clients.ad_tag is the UI projection), is rendered into
  the fork's [secret-ad-tags] section for active secrets only (mtg rejects
  a config whose override names an unknown secret), is pushed per entry
  through PUT /secrets, and is part of the reload fingerprint so a tag
  edit hot-applies without dropping connections.
- The loopback management API can replace the whole secret set, so every
  mtg process now gets a random per-process api-token; the manager sends
  it as a bearer token on PUT /secrets and GET /stats and reuses it across
  config rewrites, because mtg reads the token only at startup.
- Malformed tags are rejected at every save path and additionally dropped
  in InstanceFromInbound: one bad tag would otherwise fail the whole
  generated config and take every client of the inbound down with it.
- SyncInbound never copied a re-keyed mtproto secret into the canonical
  clients table, so the clients page and subscription links kept serving
  the old secret, which mtg then rejects. It is now guarded-copied like
  the other credentials.

frontend/src/pages/clients/ClientFormModal.tsx

@@ -119,6 +119,7 @@ interface FormState {
   wgPreSharedKey: string;
   wgAllowedIPs: string;
   secret: string;
+  adTag: string;
 }
 
 function emptyForm(): FormState {
@@ -148,6 +149,7 @@ function emptyForm(): FormState {
     wgPreSharedKey: '',
     wgAllowedIPs: '',
     secret: '',
+    adTag: '',
   };
 }
 
@@ -253,6 +255,7 @@ export default function ClientFormModal({
         wgPreSharedKey: client.preSharedKey || '',
         wgAllowedIPs: client.allowedIPs || '',
         secret: client.secret || '',
+        adTag: client.adTag || '',
       };
       if (et < 0) {
         next.delayedStart = true;
@@ -538,7 +541,13 @@ export default function ClientFormModal({
     }
 
     if (showMtproto) {
+      const adTag = form.adTag.trim();
+      if (adTag !== '' && !/^[0-9a-fA-F]{32}$/.test(adTag)) {
+        messageApi.error(t('pages.inbounds.form.mtgAdTagInvalid'));
+        return;
+      }
       clientPayload.secret = form.secret;
+      clientPayload.adTag = adTag;
     }
 
     const externalLinks: ExternalLinkInput[] = form.externalLinks
@@ -862,12 +871,22 @@ export default function ClientFormModal({
                       </>
                     )}
                     {showMtproto && (
-                      <Form.Item label={t('pages.clients.mtprotoSecret')} extra={t('pages.clients.mtprotoSecretHint')}>
-                        <Space.Compact style={{ display: 'flex' }}>
-                          <Input value={form.secret} style={{ flex: 1 }} onChange={(e) => update('secret', e.target.value)} />
-                          <Button aria-label={t('regenerate')} icon={<ReloadOutlined />} onClick={regenerateMtprotoSecret} />
-                        </Space.Compact>
-                      </Form.Item>
+                      <>
+                        <Form.Item label={t('pages.clients.mtprotoSecret')} extra={t('pages.clients.mtprotoSecretHint')}>
+                          <Space.Compact style={{ display: 'flex' }}>
+                            <Input value={form.secret} style={{ flex: 1 }} onChange={(e) => update('secret', e.target.value)} />
+                            <Button aria-label={t('regenerate')} icon={<ReloadOutlined />} onClick={regenerateMtprotoSecret} />
+                          </Space.Compact>
+                        </Form.Item>
+                        <Form.Item label={t('pages.clients.mtprotoAdTag')} extra={t('pages.clients.mtprotoAdTagHint')}>
+                          <Input
+                            value={form.adTag}
+                            allowClear
+                            placeholder="0123456789abcdef0123456789abcdef"
+                            onChange={(e) => update('adTag', e.target.value)}
+                          />
+                        </Form.Item>
+                      </>
                     )}
                   </>
                 ),