feat: 新增搜索历史与AI智能体搜索功能

- 新增搜索历史记录功能，使用 SharedPreferences + JSON 进行本地存储。
- 搜索页在无搜索结果时展示历史记录，支持点击搜索、长按删除单个记录和清空全部历史。
- 新增 "AI" 搜索标签页，用于根据关键字搜索智能体（Agent）。
- 搜索页离开时自动重置搜索状态和文本，返回后显示历史记录。
- 优化了搜索逻辑，在输入文本为空时自动隐藏搜索结果并显示历史记录。

app/src/main/java/com/aiosman/ravenow/entity/Agent.kt

@@ -90,6 +90,35 @@ class AgentPagingSource(
 
 }
 
+/**
+ * 智能体搜索分页加载器（按标题关键字）
+ */
+class AgentSearchPagingSource(
+    private val agentRemoteDataSource: AgentRemoteDataSource,
+    private val keyword: String,
+) : PagingSource<Int, AgentEntity>() {
+    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, AgentEntity> {
+        return try {
+            val currentPage = params.key ?: 1
+            val agents = agentRemoteDataSource.searchAgentByTitle(
+                pageNumber = currentPage,
+                title = keyword
+            )
+            LoadResult.Page(
+                data = agents?.list ?: listOf(),
+                prevKey = if (currentPage == 1) null else currentPage - 1,
+                nextKey = if (agents?.list?.isNotEmpty() == true) currentPage + 1 else null
+            )
+        } catch (exception: IOException) {
+            LoadResult.Error(exception)
+        }
+    }
+
+    override fun getRefreshKey(state: PagingState<Int, AgentEntity>): Int? {
+        return state.anchorPosition
+    }
+}
+
 
 class AgentRemoteDataSource(
     private val agentService: AgentService,
@@ -103,6 +132,16 @@ class AgentRemoteDataSource(
             authorId = authorId
         )
     }
+
+    suspend fun searchAgentByTitle(
+        pageNumber: Int,
+        title: String
+    ): ListContainer<AgentEntity>? {
+        return agentService.searchAgentByTitle(
+            pageNumber = pageNumber,
+            title = title
+        )
+    }
 }
 
 class AgentServiceImpl() : AgentService {
@@ -118,6 +157,17 @@ class AgentServiceImpl() : AgentService {
             authorId = authorId
         )
     }
+
+    override suspend fun searchAgentByTitle(
+        pageNumber: Int,
+        pageSize: Int,
+        title: String
+    ): ListContainer<AgentEntity>? {
+        return agentBackend.searchAgentByTitle(
+            pageNumber = pageNumber,
+            title = title
+        )
+    }
 }
 
 class AgentBackend {
@@ -175,6 +225,27 @@ class AgentBackend {
             )
         }
     }
+
+    suspend fun searchAgentByTitle(
+        pageNumber: Int,
+        title: String
+    ): ListContainer<AgentEntity>? {
+        val resp = ApiClient.api.getAgent(
+            page = pageNumber,
+            pageSize = DataBatchSize,
+            withWorkflow = 1,
+            title = title
+        )
+        val body = resp.body() ?: return null
+        val dataContainer = body as DataContainer<ListContainer<Agent>>
+        val listContainer = dataContainer.data
+        return ListContainer(
+            total = listContainer.total,
+            page = pageNumber,
+            pageSize = DataBatchSize,
+            list = listContainer.list.map { it.toAgentEntity() }
+        )
+    }
 }
 
 data class AgentEntity(