feat(ai): 知识库 V2 菜单迁移 + 文本切片器 + 前端路由权限

- 新增迁移 000168：在 AI 知识库同级添加「知识库 V2」菜单，绑定 admin 角色
- 新增 document/chunker.rs：固定大小 + overlap 文本切片器（5 单元测试）
- 前端 routeConfig 添加 /health/ai-knowledge-v2 权限声明
- App.tsx validateRouteCoverage 补充 v2 路径

crates/erp-ai/src/service/document/chunker.rs

@@ -0,0 +1,87 @@
+/// 文本切片：按固定大小 + 重叠切分
+pub fn chunk_text(text: &str, chunk_size: usize, overlap: usize) -> Vec<String> {
+    if text.is_empty() {
+        return vec![];
+    }
+
+    let chars: Vec<char> = text.chars().collect();
+    let total = chars.len();
+
+    if total <= chunk_size {
+        return vec![text.to_string()];
+    }
+
+    let mut chunks = Vec::new();
+    let mut start = 0;
+
+    while start < total {
+        let end = (start + chunk_size).min(total);
+        let chunk: String = chars[start..end].iter().collect();
+
+        let trimmed = chunk.trim().to_string();
+        if !trimmed.is_empty() {
+            chunks.push(trimmed);
+        }
+
+        if end >= total {
+            break;
+        }
+        start += chunk_size.saturating_sub(overlap);
+
+        // 防止无限循环
+        if start <= end - chunk_size && start > 0 {
+            start = end;
+        }
+    }
+
+    chunks
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_chunk_empty() {
+        assert_eq!(chunk_text("", 100, 20), Vec::<String>::new());
+    }
+
+    #[test]
+    fn test_chunk_small_text() {
+        let text = "hello world";
+        let chunks = chunk_text(text, 100, 20);
+        assert_eq!(chunks.len(), 1);
+        assert_eq!(chunks[0], "hello world");
+    }
+
+    #[test]
+    fn test_chunk_long_text() {
+        let text = "abcdefghij".repeat(100); // 1000 chars
+        let chunks = chunk_text(&text, 200, 50);
+        assert!(chunks.len() > 1);
+        // First chunk should be 200 chars
+        assert_eq!(chars_count(&chunks[0]), 200);
+    }
+
+    #[test]
+    fn test_chunk_with_overlap() {
+        let text = "abcdefghijklmnopqrstuvwxyz".repeat(20); // 520 chars
+        let chunks = chunk_text(&text, 100, 20);
+        assert!(chunks.len() > 1);
+    }
+
+    #[test]
+    fn test_chunk_chinese() {
+        let text = "你好世界这是一段中文测试文本。".repeat(30);
+        let chunks = chunk_text(&text, 100, 20);
+        assert!(chunks.len() > 1);
+        // 确保中文不被截断
+        for chunk in &chunks {
+            assert!(!chunk.is_empty());
+        }
+    }
+
+    fn chars_count(s: &str) -> usize {
+        s.chars().count()
+    }
+}

crates/erp-ai/src/service/mod.rs

@@ -7,6 +7,7 @@ pub mod chat_session;
 pub mod comparison;
 pub mod cost;
 pub mod dialysis_risk_scorer;
+pub mod document;
 pub mod embedding;
 pub mod feature_flag_service;
 pub mod insight_service;