fix(auth): 公开登录门按来源限速并设全站发信上限，冷却表定期清理

deploy/alerts/felis-prometheusrule.yaml

@@ -98,3 +98,49 @@ spec:
               --collector.textfile.directory at the directory of
               FELIS_DB_BACKUP_METRICS (default /var/lib/node_exporter/textfile_collector)
               (troubleshooting §16).
+    - name: felis.auth.rules
+      rules:
+        - alert: FelisMailBudgetExhausted
+          expr: sum(increase(felis_mail_total{result="throttled"}[15m])) > 0
+          labels:
+            severity: warning
+          annotations:
+            summary: "the install-wide mail budget refused mail"
+            description: >-
+              felis_mail_total{result="throttled"} increased: [smtp] max_per_hour is
+              spent, and every sign-in code is refused with 429 mail_rate_limited until
+              it refills. Check felis_rate_limited_total for a flood before raising the
+              budget (troubleshooting §17).
+        - alert: FelisMailDeliveryFailing
+          expr: sum(increase(felis_mail_total{result="failed"}[15m])) > 0
+          labels:
+            severity: warning
+          annotations:
+            summary: "the SMTP relay refused mail in the last 15m"
+            description: >-
+              felis_mail_total{result="failed"} increased: sign-in codes are not being
+              delivered (502 mail_undeliverable). The relay's reason is in the
+              felis-api log (troubleshooting §17).
+        - alert: FelisSignInFlood
+          expr: sum(rate(felis_rate_limited_total{scope="auth_door"}[5m])) * 60 > 10
+          for: 10m
+          labels:
+            severity: warning
+          annotations:
+            summary: "sign-in doors refusing over 10 requests a minute"
+            description: >-
+              The per-address sign-in limit has been refusing callers for 10 minutes.
+              A script is hammering the auth doors; if real users report rate_limited
+              at once instead, [auth] client_ip_header is missing and everyone shares
+              the proxy's address (troubleshooting §17).
+        - alert: FelisOTPAccountLocked
+          expr: sum by (purpose) (increase(felis_auth_otp_lockouts_total[1h])) > 0
+          labels:
+            severity: warning
+          annotations:
+            summary: "an account's email-code sign-in locked after 10 wrong codes"
+            description: >-
+              Someone entered 10 wrong codes for one account within 24h ({{ $labels.purpose }}).
+              The audit log names the account (action auth.otp.locked); the owner was
+              mailed. Unless they fumbled codes, someone is guessing at it
+              (troubleshooting §17).