feat(ai-core): mood state machine and affection level

- new emotion package: rule-based sentiment (positive/negative lexicon)
  drives mood transitions (开心/平静/难过) with 30min inactivity decay;
  affection 0-100 grows with positive interaction, with 初识→熟悉→信赖→
  羁绊 tiers
- pipeline records each user message and injects a mood line into the
  system prompt so the persona's tone follows her mood
- mood changes broadcast over WS; frontend shows a mood badge with
  affection tooltip; also handles the 'reminder' message type from the
  reminder scheduler
- tests: sentiment scoring, mood shift, affection bounds, prompt line,
  onChange callback

backend/cmd/cyrene/main.go

@@ -33,6 +33,7 @@ import (
 	websearch "git.yeij.top/AskaEth/Cyrene_v2/plugins/web-search"
 
 	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/background"
+	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/emotion"
 	"git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/llm"
 	llmlog "git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/llm"
 	tracepkg "git.yeij.top/AskaEth/Cyrene_v2/services/ai-core/trace"
@@ -262,6 +263,11 @@ func main() {
 	thinker.Start(context.Background())
 	orch.SetPostChatHook(thinker.TriggerPostChat)
 
+	// === 12.6 Emotion tracker ===
+	emotionTracker := emotion.NewTracker()
+	orch.SetEmotionTracker(emotionTracker)
+	logger.Infof("[emotion] tracker ready (mood=%s)", emotionTracker.Snapshot().Mood)
+
 	// === 12.6 Memory decay scheduler ===
 	if memSvc != nil {
 		go func() {
@@ -307,6 +313,14 @@ func main() {
 		}
 	}()
 
+	// Broadcast mood changes to web clients
+	emotionTracker.OnChange(func(s emotion.Snapshot) {
+		wsHub.Broadcast(map[string]any{
+			"type": "mood", "mood": string(s.Mood),
+			"intensity": s.Intensity, "affection": s.Affection,
+		})
+	})
+
 	// === 12.7 Automation engine ===
 	autoEngine := engine.New(
 		automationSourceAdapter{gwDeps.Automation},