feat: add SEND_MAIL delivery and quota controls (#986)

* feat: add SEND_MAIL delivery and quota controls

* test: cover -1 unlimited runtime for send mail quota

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* fix: split send limit validation and save

* refactor: move send limit counters to settings

* fix: polish send mail limit review follow-ups

* docs: note SEND_MAIL breaking change

* test: align send mail limit e2e with new messages

* fix: address review follow-ups

* fix: harden admin send mail handlers

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Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

worker/src/i18n/en.ts

@@ -71,7 +71,9 @@ const messages: LocaleMessages = {
     ContentEmptyMsg: "Content is empty",
     AlreadyRequestedMsg: "Already requested",
     EnableResendOrSmtpMsg: "Please enable resend or smtp for this domain",
-    EnableResendOrSmtpWithVerifiedMsg: "Please enable resend or smtp for this domain, or add recipient to verified address list",
+    EnableResendOrSmtpOrSendMailMsg: "Please enable resend, smtp or SEND_MAIL for this domain",
+    ServerSendMailDailyLimitMsg: "Server daily send quota has been reached",
+    ServerSendMailMonthlyLimitMsg: "Server monthly send quota has been reached",
     InvalidToMailMsg: "Invalid recipient address",
 
     // Admin related

worker/src/i18n/type.ts

@@ -69,7 +69,9 @@ export type LocaleMessages = {
     ContentEmptyMsg: string
     AlreadyRequestedMsg: string
     EnableResendOrSmtpMsg: string
-    EnableResendOrSmtpWithVerifiedMsg: string
+    EnableResendOrSmtpOrSendMailMsg: string
+    ServerSendMailDailyLimitMsg: string
+    ServerSendMailMonthlyLimitMsg: string
     InvalidToMailMsg: string
 
     // Admin related

worker/src/i18n/zh.ts

@@ -71,7 +71,9 @@ const messages: LocaleMessages = {
     ContentEmptyMsg: "内容不能为空",
     AlreadyRequestedMsg: "已经申请过了",
     EnableResendOrSmtpMsg: "请先为此域名启用 resend 或 smtp",
-    EnableResendOrSmtpWithVerifiedMsg: "请先为此域名启用 resend 或 smtp，或将收件人添加到已验证地址列表",
+    EnableResendOrSmtpOrSendMailMsg: "请先为此域名启用 resend、smtp 或 SEND_MAIL",
+    ServerSendMailDailyLimitMsg: "服务器今日发信次数已达上限",
+    ServerSendMailMonthlyLimitMsg: "服务器本月发信次数已达上限",
     InvalidToMailMsg: "收件人地址无效",
 
     // Admin related