fix(captcha): seal comment fallback and phone-register client loop

Gate preprocess_comment so native wp-comments-post cannot bypass captcha,
require verify+reset on phone register, and align UsersSignin status with
active provider.

assets/js/sign-register.js

@@ -205,35 +205,53 @@
       submitBtn.textContent = '注册中...'
     }
 
-    const captchaData = collectCaptchaFields(form)
-
-    fetch(REST_BASE + '/auth/phone-register', {
-      method: 'POST',
-      headers: { 'Content-Type': 'application/json' },
-      body: JSON.stringify({ phone, code, password, invite_code: inviteCode, ...captchaData }),
-    })
-      .then(r => r.json().then(data => ({ ok: r.ok, data })))
-      .then(({ ok, data }) => {
-        if (ok && data.success) {
-          showToast(data.message || '注册成功', 'success')
-          setTimeout(() => {
-            window.location.href = data.data?.redirect || '/'
-          }, 500)
-        } else {
-          showToast(data.message || '注册失败', 'error')
+    const captchaState = window.AKSRTCaptchaState
+    const doRegister = () => {
+      const captchaData = collectCaptchaFields(form)
+      fetch(REST_BASE + '/auth/phone-register', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ phone, code, password, invite_code: inviteCode, ...captchaData }),
+      })
+        .then(r => r.json().then(data => ({ ok: r.ok, data })))
+        .then(({ ok, data }) => {
+          if (ok && data.success) {
+            showToast(data.message || '注册成功', 'success')
+            setTimeout(() => {
+              window.location.href = data.data?.redirect || '/'
+            }, 500)
+          } else {
+            showToast(data.message || '注册失败', 'error')
+            try {
+              if (captchaState && captchaState.scenes && captchaState.scenes.register) {
+                captchaState.scenes.register.reset()
+              }
+            } catch (e) { /* ignore */ }
+            if (submitBtn) {
+              submitBtn.disabled = false
+              submitBtn.textContent = '注册'
+            }
+          }
+        })
+        .catch(() => {
+          showToast('网络错误', 'error')
+          try {
+            if (captchaState && captchaState.scenes && captchaState.scenes.register) {
+              captchaState.scenes.register.reset()
+            }
+          } catch (e) { /* ignore */ }
           if (submitBtn) {
             submitBtn.disabled = false
             submitBtn.textContent = '注册'
           }
-        }
-      })
-      .catch(() => {
-        showToast('网络错误', 'error')
-        if (submitBtn) {
-          submitBtn.disabled = false
-          submitBtn.textContent = '注册'
-        }
-      })
+        })
+    }
+
+    if (captchaState && captchaState.scenes && captchaState.scenes.register) {
+      captchaState.scenes.register.verify(doRegister)
+    } else {
+      doRegister()
+    }
   }
 
   function handlePhoneLogin(form) {