后端：资料距离、语音图片会员限制、免短信注册、AI 托管回复修复

- 单用户资料接口补上距离：此前只有推荐/附近列表会算距离，资料页和
  聊天头部因此无内容可显示。沿用同一套 haversine 与隐私开关。
- 语音/图片消息可限定会员发送，两个开关在管理端「运营配置」中修改
  （迁移 032）。校验放在 persistMessageContext，HTTP 与 WebSocket
  两条发送路径都覆盖；文本消息永不受限。
- 短信服务关闭时注册不再要求验证码：关掉之后没人能拿到验证码，继续
  要求就等于关闭注册通道。重置密码不做同样放宽，那里缺验证码等于
  凭手机号夺号。app/config 增加 smsVerification 供客户端决定表单形态。
- 修复 AI 托管账号之间不回复：原规则按「发送方是否托管账号」拦截，
  把真人操作测试号的正常对话也挡了。改为标记 worker 自己写入的回复，
  只对 AI 生成的消息跳过入队。
- ai.default_model_id 同时接受模型 ID 与名称，填名称时不再被 MySQL
  静默转成 0 而使配置失效。
- 聊天媒体留存管理与清理任务（迁移 033，两台线上均已应用）。

新增集成测试均针对真实 MySQL：会员限制、免短信注册、AI 入队规则、
默认模型解析、资料距离。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

im/backend/internal/app/ai_agent.go

@@ -43,10 +43,28 @@ type aiReplyJob struct {
 // Called right after a message is committed, from every send path. It must stay
 // cheap and must never fail the send: a missing reply is better than a failed
 // message.
+// aiGeneratedKey marks the context in which the worker writes its own reply.
+// The loop it prevents is "a reply triggers another reply", which is a property
+// of the message, not of the account: a person operating a managed test account
+// is having a real conversation and deserves an answer.
+type aiGeneratedKey struct{}
+
+func markAIGenerated(ctx context.Context) context.Context {
+	return context.WithValue(ctx, aiGeneratedKey{}, true)
+}
+
+func isAIGenerated(ctx context.Context) bool {
+	value, _ := ctx.Value(aiGeneratedKey{}).(bool)
+	return value
+}
+
 func (a *App) enqueueAIReply(ctx context.Context, conversationID, senderID int64, members []int64, messageID int64) {
 	if !a.configBool(ctx, "ai.enabled", false) {
 		return
 	}
+	if isAIGenerated(ctx) {
+		return // The worker's own reply must never trigger the next one.
+	}
 	peerID := int64(0)
 	for _, member := range members {
 		if member != senderID {
@@ -61,13 +79,14 @@ func (a *App) enqueueAIReply(ctx context.Context, conversationID, senderID int64
 	}
 	var agentUserID int64
 	var testBatch string
-	// The sender must not itself be managed, otherwise two agents would keep
-	// each other talking forever.
+	// Note there is no condition on the sender: whoever typed this, the reply is
+	// owed by the recipient. Runaway agent-to-agent chatter is prevented above,
+	// where the worker's own writes are recognised and skipped, and bounded by
+	// the per-agent daily reply limits.
 	err := a.db.QueryRowContext(ctx, `SELECT g.user_id,u.test_batch
 		FROM ai_agents g JOIN users u ON u.id=g.user_id
-		WHERE g.user_id=? AND g.enabled=1 AND u.is_test=1 AND u.status=1 AND u.deleted_at IS NULL
-		AND NOT EXISTS(SELECT 1 FROM ai_agents s WHERE s.user_id=? AND s.enabled=1)`,
-		peerID, senderID).Scan(&agentUserID, &testBatch)
+		WHERE g.user_id=? AND g.enabled=1 AND u.is_test=1 AND u.status=1 AND u.deleted_at IS NULL`,
+		peerID).Scan(&agentUserID, &testBatch)
 	if err != nil || agentUserID == 0 {
 		return
 	}
@@ -260,7 +279,7 @@ func (a *App) processAIReplyJob(ctx context.Context, job aiReplyJob) error {
 }
 
 func (a *App) sendAIReply(ctx context.Context, job aiReplyJob, text string) error {
-	item, members, err := a.persistMessageContext(ctx, job.ConversationID, job.AgentUserID,
+	item, members, err := a.persistMessageContext(markAIGenerated(ctx), job.ConversationID, job.AgentUserID,
 		"ai-"+randomToken()[:20], 1, map[string]any{"text": text})
 	if err != nil {
 		return err