fix: 消息日志增强 + 历史消息抑制 + SSE实时追踪 + 群聊上下文优化

- 日志：收/发消息均显示群名称，管理员显示真实QQ昵称而非"开拓者"
- 历史消息：服务重启后NapCat回放的历史消息不再触发回复，静默注入上下文
- 消息时间戳：转发给AI时附带【消息时间: HH:MM:SS (XmXs前)】标记
- ♪ 分割符：QQ消息支持♪作为句子断点
- AI-Core SSE端点：全链路追踪实时推送，ethend不再5秒轮询
- 群聊上下文：AI-Core明确被告知消息来自群聊，以实际发送者为主语

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

backend/platform-bridge/internal/bridge/router.go

@@ -4,10 +4,14 @@ import (
 	"context"
 	"fmt"
 	"sync"
+	"time"
 
 	"git.yeij.top/AskaEth/Cyrene/platform-bridge/internal/permissions"
 )
 
+
+const participantTTL = 5 * time.Minute
+
 // adapterKey returns the unique key for an adapter in the router map.
 // Uses ConfigName() if the adapter implements it, otherwise PlatformName().
 func adapterKey(a PlatformAdapter) string {
@@ -31,13 +35,14 @@ type PlatformRouter struct {
 
 // ChannelContext stores the active conversation state for a channel.
 type ChannelContext struct {
-	Platform      string
-	ChannelID     string
-	ChannelType   string
-	LastUserMsg   string
-	LastSenderUID string
-	RecentSenders []string // last 5 sender UIDs (original platform UIDs)
-	MessageCount  int
+	Platform            string
+	ChannelID           string
+	ChannelType         string
+	LastUserMsg         string
+	LastSenderUID       string
+	RecentSenders       []string // last 5 sender UIDs (original platform UIDs)
+	ActiveParticipants map[string]time.Time // UID -> last bot reply time (for multi-user conversation continuity)
+	MessageCount        int
 }
 
 func NewPlatformRouter(mapper *IdentityMapper, checker *permissions.Checker) *PlatformRouter {
@@ -137,6 +142,7 @@ func (r *PlatformRouter) RouteMessage(adapterKey string, rawMsg interface{}) (*U
 
 	// Preserve original platform UID before identity mapping.
 	unified.OriginalSenderUID = unified.SenderID
+	unified.OriginalSenderName = unified.SenderName
 	unified.OriginalRawMessage = rawMsg
 
 	// Capture bot's own UID for @mention detection.
@@ -228,3 +234,37 @@ func (r *PlatformRouter) GetContext(platform, channelID string) *ChannelContext
 	defer r.mu.RUnlock()
 	return r.contexts[platform+":"+channelID]
 }
+
+// NoteBotReply records that the bot just replied to a specific user in a channel.
+// Used for conversation continuity: subsequent messages from this user continue the
+// conversation even without an explicit @mention, within the participant TTL window.
+func (r *PlatformRouter) NoteBotReply(platform, channelID, recipientUID string) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	key := r.channelKey(platform, channelID)
+	ctx, ok := r.contexts[key]
+	if !ok {
+		return
+	}
+	if ctx.ActiveParticipants == nil {
+		ctx.ActiveParticipants = make(map[string]time.Time)
+	}
+	ctx.ActiveParticipants[recipientUID] = time.Now()
+}
+
+// IsActiveParticipant checks if a user was recently engaged by the bot.
+// TTL controls how long the continuity window stays open after the last bot reply.
+func (r *PlatformRouter) IsActiveParticipant(platform, channelID, uid string) bool {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+	key := r.channelKey(platform, channelID)
+	ctx, ok := r.contexts[key]
+	if !ok || ctx.ActiveParticipants == nil {
+		return false
+	}
+	t, ok := ctx.ActiveParticipants[uid]
+	if !ok {
+		return false
+	}
+	return time.Since(t) < participantTTL
+}