docs(comments): 注释中文化 · internal/runtime/history（15 文件，纯替换）

- 只翻注释/文档字符串：剥离注释后代码行逐字节不变（机械校验只剩 4 条行尾注释的翻译，代码前缀全等）
- 交叉引用（design/16 §4.6、D4/B3、0010 迁移文件名）逐字保留
- 保留未译技术词：DDL/rowid/LIKE/LEFT JOIN/DTO/rune/WS/actor 及全部标识符与表名
- 顺带副作用：store.go、session_persona_test.go 由注释文字改变而变得 gofmt 干净（未运行 gofmt -w）

internal/runtime/history/title.go

@@ -7,30 +7,27 @@ import (
 	"strings"
 )
 
-// This file owns the two session-title paths: auto-naming a session from its first
-// user message and an explicit rename. A title is display-only metadata (design/16
-// §2.1) and is never used to identify a session, a sender or a permission — identity
-// always comes from the channel actor metadata / JWT (project red line).
+// 本文件负责两条会话标题路径：从第一条用户消息为会话自动命名，以及显式
+// 重命名。标题只是展示元数据（design/16 §2.1），绝不用于标识会话、发送者
+// 或权限 —— 身份永远来自渠道 actor 元数据 / JWT（项目红线）。
 
 const (
-	// autoTitleMaxRunes bounds an auto-generated title so a session list row never
-	// overflows; a longer first message is truncated with an ellipsis.
+	// autoTitleMaxRunes 限制自动生成标题的长度，使会话列表行不会溢出；
+	// 更长的首条消息会被截断并加省略号。
 	autoTitleMaxRunes = 20
-	// titleMainFallback and titleSubFallback name a session whose first user
-	// message carries no text (e.g. an image-only turn), so the session list is
-	// never nameless.
+	// titleMainFallback 与 titleSubFallback 用于给首条用户消息没有任何
+	// 文本的会话（例如纯图片回合）命名，使会话列表不会无名。
 	titleMainFallback = "主会话"
 	titleSubFallback  = "次级会话"
 )
 
-// ErrSessionNotFound is returned by RenameSession when no chat_sessions row carries
-// the requested id.
+// ErrSessionNotFound 在没有任何 chat_sessions 行携带所请求 id 时由
+// RenameSession 返回。
 var ErrSessionNotFound = errors.New("history: session not found")
 
-// RenameSession sets the display title of sessionID. Both the fixed main session
-// (id "web") and sub sessions may be renamed: renaming is not a destructive identity
-// change, unlike deletion. An unknown id returns ErrSessionNotFound. The caller
-// validates the title (non-empty, length-bounded); the store persists it verbatim.
+// RenameSession 设置 sessionID 的显示标题。固定主会话（id "web"）与子会话
+// 都可重命名：与删除不同，重命名不是破坏性的身份变更。未知 id 返回
+// ErrSessionNotFound。标题由调用方校验（非空、限长）；存储原样持久化它。
 func (s *Store) RenameSession(ctx context.Context, sessionID, title string) error {
 	res, err := s.db.ExecContext(ctx, `UPDATE chat_sessions SET title = ? WHERE id = ?`, title, sessionID)
 	if err != nil {
@@ -46,12 +43,11 @@ func (s *Store) RenameSession(ctx context.Context, sessionID, title string) erro
 	return nil
 }
 
-// ensureTitle names a session from its first user message. It is a no-op unless the
-// session row exists in chat_sessions, its title is still empty, and no user message
-// has been persisted for it yet (so the caller must invoke it before inserting the
-// message). A message that is all whitespace falls back to the session-type label.
-// The title is display-only metadata, so a failure is logged and swallowed rather
-// than failing the message write it accompanies.
+// ensureTitle 用第一条用户消息为会话命名。除非该会话行已存在于
+// chat_sessions、其标题仍为空、且尚未为它持久化任何用户消息（因此调用方
+// 必须在插入消息之前调用它），否则它是空操作。纯空白的消息回退到会话类型
+// 标签。标题只是展示元数据，因此失败只记日志并吞掉，而不是让它伴随的
+// 消息写入失败。
 func (s *Store) ensureTitle(ctx context.Context, sessionID, content string) {
 	if sessionID == "" {
 		return
@@ -68,10 +64,9 @@ func (s *Store) ensureTitle(ctx context.Context, sessionID, content string) {
 	}
 }
 
-// deriveTitle turns a user message into a session title: whitespace runs (newlines
-// included) collapse to a single space, then the result is truncated to
-// autoTitleMaxRunes runes with an ellipsis. A message that is all whitespace yields
-// "" so ensureTitle falls back to the session-type label.
+// deriveTitle 把一条用户消息变成会话标题：空白串（含换行）折叠为单个空格，
+// 再把结果截断到 autoTitleMaxRunes 个 rune 并加省略号。纯空白的消息得到
+// 空串，使 ensureTitle 回退到会话类型标签。
 func deriveTitle(content string) string {
 	fields := strings.Fields(content)
 	if len(fields) == 0 {