feat: 人格文档双层架构 — persona.md全量注入system prompt + RAG黑名单过滤

- PersonaConfig 新增 NarrativePersona 字段，在 system prompt 的「你的身份」和「你的性格」之间插入「## 你的叙事人格」
- Loader.NewLoader 自动读取同目录 persona.md 注入所有 config；Reload 同步热更新
- RAG IngestDirectory 跳过 persona.md 和 _index.md，避免重复检索浪费token
- 新增 docs/dev-plan/12-next-phase-optimization.md 下一阶段优化大纲

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

backend/ai-core/internal/persona/injector.go

@@ -17,6 +17,11 @@ type PersonaConfig struct {
     ThinkingGuidelines  ThinkingGuidelines    `yaml:"thinking_guidelines"`
     MemoryGuidelines    MemoryGuidelines      `yaml:"memory_guidelines"`
     ReflectionGuidelines ReflectionGuidelines `yaml:"reflection_guidelines"`
+
+    // NarrativePersona is the full text of persona.md, injected verbatim
+    // into the system prompt as the narrative personality layer.
+    // Not parsed from YAML — loaded from persona.md alongside the YAML config.
+    NarrativePersona string `yaml:"-"`
 }
 
 // BuildSystemPrompt 构建系统Prompt (向后兼容，不含心情)
@@ -43,8 +48,11 @@ func (pc *PersonaConfig) BuildSystemPromptWithMood(userName string, affectionLev
 ## 你的身份
 %s
 
+## 你的叙事人格
+%s
+
 ## 你的性格
-`, pc.Identity.TrueName, pc.Identity.Essence)
+`, pc.Identity.TrueName, pc.Identity.Essence, pc.NarrativePersona)
 
     for _, trait := range pc.Personality.CoreTraits {
         prompt += fmt.Sprintf("- %s: %s\n", trait.Name, trait.Description)

backend/ai-core/internal/persona/loader.go

@@ -3,6 +3,7 @@ package persona
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 	"sync"
 
 	"gopkg.in/yaml.v3"
@@ -54,6 +55,17 @@ func NewLoader(personaDir string) (*Loader, error) {
 		return nil, fmt.Errorf("未找到任何人格配置文件")
 	}
 
+	// Load narrative persona from persona.md (same directory as YAML configs).
+	// This is the full-text personality narrative injected verbatim into the system prompt.
+	personaMDPath := filepath.Join(personaDir, "persona.md")
+	if data, err := os.ReadFile(personaMDPath); err == nil {
+		// Attach to every loaded persona config.
+		narrative := string(data)
+		for _, cfg := range l.configs {
+			cfg.NarrativePersona = narrative
+		}
+	}
+
 	return l, nil
 }
 
@@ -82,6 +94,12 @@ func (l *Loader) Reload(name string, path string) error {
 	}
 
 	l.mu.Lock()
+	// Re-read persona.md to keep narrative persona in sync.
+	personaDir := filepath.Dir(path)
+	personaMDPath := filepath.Join(personaDir, "persona.md")
+	if data, err := os.ReadFile(personaMDPath); err == nil {
+		cfg.NarrativePersona = string(data)
+	}
 	l.configs[name] = &cfg
 	l.mu.Unlock()