feat(mind): add emotion entity fields and trend/scatter point DTOs

Add arousalLevel, energyLevel, stressLevel, sleep fields to EmotionCheckin entity. Create MoodTrendPoint and AffectPoint DTOs for trend visualization.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

cfc-backend/src/main/java/com/etotem/cfc/dto/AffectPoint.java

@@ -0,0 +1,12 @@
+package com.etotem.cfc.dto;
+
+import lombok.Data;
+
+import java.io.Serializable;
+
+@Data
+public class AffectPoint implements Serializable {
+    private String date;
+    private Integer valence;
+    private Integer arousal;
+}

cfc-backend/src/main/java/com/etotem/cfc/dto/MoodTrendPoint.java

@@ -0,0 +1,11 @@
+package com.etotem.cfc.dto;
+
+import lombok.Data;
+
+import java.io.Serializable;
+
+@Data
+public class MoodTrendPoint implements Serializable {
+    private String date;
+    private Integer moodScore;
+}

cfc-backend/src/main/java/com/etotem/cfc/entity/EmotionCheckin.java

@@ -38,4 +38,14 @@ public class EmotionCheckin implements Serializable {
     private String emotionType;
 
     private Integer stressLevel;
+
+    // === Phase 1.1 新增字段 ===
+    private Integer arousalLevel;
+
+    private Integer energyLevel;
+
+    // === Phase 3.1 预埋字段 ===
+    private Float sleepHours;
+
+    private Integer sleepQuality;
 }