feat: paginate, sync, and display branched sessions (#563)

* mobile: 以 Desktop Sessions 作为聊天历史源

* mobile: 修复快速连接崩溃与无标题会话隐藏

* mobile: 对齐 Desktop 标题并恢复完整历史

* mobile: 分离 Desktop 存储 ID 与运行 Session ID

* mobile: 将新对话持久化为 Desktop Session

* mobile: 渲染 Desktop 本地媒体

* feat: 分页加载并同步当前会话

* fix: 显示分支会话名称与层级

* fix: align PR with upstream app contract

* fix: preserve upstream session RPC lifecycle

app/src/main/java/com/m57/hermescontrol/data/remote/HermesApiService.kt

@@ -131,6 +131,8 @@ interface HermesApiService {
         // Preserve slashes in session IDs — backend generates IDs containing '/' characters (issue #468).
         // Contract: The server-generated sessionId must only contain URL-safe characters (no ?, #, or spaces).
         @Path("id", encoded = true) sessionId: String,
+        @Query("limit") limit: Int? = null,
+        @Query("offset") offset: Int = 0,
     ): Response<SessionMessagesResponse>
 
     @GET("api/sessions/stats")