feat: add affiliate invite rebate flow and admin rebate-rate setting

frontend/src/views/auth/EmailVerifyView.vue

@@ -209,6 +209,7 @@ const password = ref<string>('')
 const initialTurnstileToken = ref<string>('')
 const promoCode = ref<string>('')
 const invitationCode = ref<string>('')
+const affCode = ref<string>('')
 const pendingAuthToken = ref<string>('')
 const pendingAuthTokenField = ref<PendingAuthTokenField>('pending_auth_token')
 const pendingProvider = ref<string>('')
@@ -260,6 +261,7 @@ onMounted(async () => {
       initialTurnstileToken.value = registerData.turnstile_token || ''
       promoCode.value = registerData.promo_code || ''
       invitationCode.value = registerData.invitation_code || ''
+      affCode.value = registerData.aff_code || ''
       pendingAuthToken.value = registerData.pending_auth_token || activePendingSession?.token || ''
       pendingAuthTokenField.value = registerData.pending_auth_token_field || activePendingSession?.token_field || 'pending_auth_token'
       pendingProvider.value = registerData.pending_provider || activePendingSession?.provider || ''
@@ -524,7 +526,8 @@ async function handleVerify(): Promise<void> {
         verify_code: verifyCode.value.trim(),
         turnstile_token: initialTurnstileToken.value || undefined,
         promo_code: promoCode.value || undefined,
-        invitation_code: invitationCode.value || undefined
+        invitation_code: invitationCode.value || undefined,
+        ...(affCode.value ? { aff_code: affCode.value } : {})
       })
     }
 

frontend/src/views/auth/RegisterView.vue

@@ -351,7 +351,8 @@ const formData = reactive({
   email: '',
   password: '',
   promo_code: '',
-  invitation_code: ''
+  invitation_code: '',
+  aff_code: ''
 })
 
 const errors = reactive({
@@ -406,6 +407,10 @@ onMounted(async () => {
         await validatePromoCodeDebounced(promoParam)
       }
     }
+    const affParam = (route.query.aff as string) || (route.query.aff_code as string)
+    if (affParam) {
+      formData.aff_code = affParam.trim()
+    }
   } catch (error) {
     console.error('Failed to load public settings:', error)
   } finally {
@@ -707,7 +712,8 @@ async function handleRegister(): Promise<void> {
           password: formData.password,
           turnstile_token: turnstileToken.value,
           promo_code: formData.promo_code || undefined,
-          invitation_code: formData.invitation_code || undefined
+          invitation_code: formData.invitation_code || undefined,
+          ...(formData.aff_code ? { aff_code: formData.aff_code } : {})
         })
       )
 
@@ -722,7 +728,8 @@ async function handleRegister(): Promise<void> {
       password: formData.password,
       turnstile_token: turnstileEnabled.value ? turnstileToken.value : undefined,
       promo_code: formData.promo_code || undefined,
-      invitation_code: formData.invitation_code || undefined
+      invitation_code: formData.invitation_code || undefined,
+      ...(formData.aff_code ? { aff_code: formData.aff_code } : {})
     })
 
     // Show success toast