feat: implement QuestionBank CRUD with pagination and template query

- Add pagination support to findAll (page, limit query params)
- Add findByTemplateId method to service
- Add GET /by-template/:templateId endpoint to controller
- Service already includes CRUD for QuestionBank and QuestionBankItem

web/services/chatService.ts

@@ -0,0 +1,166 @@
+import { apiClient } from './apiClient';
+
+export interface ChatMessage {
+  role: 'user' | 'assistant';
+  content: string;
+}
+
+export interface ChatSource {
+  fileName: string;
+  title?: string;
+  content: string;
+  score: number;
+  chunkIndex: number;
+  fileId?: string;
+}
+
+export class ChatService {
+  async *streamChat(
+    message: string,
+    history: ChatMessage[],
+    authToken: string,
+    userLanguage: string = 'zh',
+    selectedEmbeddingId?: string,
+    selectedLLMId?: string, // Added: Selected LLM ID
+    selectedGroups?: string[], // Added: Selected groups
+    selectedFiles?: string[], // Added: Selected files
+    historyId?: string, // Added: Conversation history ID
+    enableRerank?: boolean, // Added: Enable Rerank
+    selectedRerankId?: string, // Added: Rerank model ID
+    temperature?: number, // Added: temperature parameter
+    maxTokens?: number, // Added: maxTokens parameter
+    topK?: number, // Added: topK parameter
+    similarityThreshold?: number, // Added: similarityThreshold parameter
+    rerankSimilarityThreshold?: number, // Added: rerankSimilarityThreshold parameter
+    enableQueryExpansion?: boolean, // Added
+    enableHyDE?: boolean // Added
+  ): AsyncGenerator<{ type: 'content' | 'sources' | 'error' | 'historyId'; data: any }> {
+    try {
+      const response = await apiClient.request('/chat/stream', {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+          'x-user-language': userLanguage || localStorage.getItem('userLanguage') || 'zh',
+        },
+        body: JSON.stringify({
+          message,
+          history,
+          userLanguage,
+          selectedEmbeddingId,
+          selectedLLMId,
+          selectedGroups,
+          selectedFiles,
+          historyId,
+          enableRerank,
+          selectedRerankId,
+          temperature,
+          maxTokens,
+          topK,
+          similarityThreshold,
+          rerankSimilarityThreshold,
+          enableQueryExpansion,
+          enableHyDE
+        }),
+      });
+
+      if (!response.ok) {
+        let errorMessage = 'Request failed';
+        try {
+          const error = await response.json();
+          errorMessage = error.error || error.message || 'Request failed';
+        } catch {
+          errorMessage = `Server error: ${response.status}`;
+        }
+        yield { type: 'error', data: errorMessage };
+        return;
+      }
+
+      const reader = response.body?.getReader();
+      if (!reader) {
+        yield { type: 'error', data: 'Cannot read response stream' };
+        return;
+      }
+
+      const decoder = new TextDecoder();
+      let buffer = '';
+
+      while (true) {
+        const { done, value } = await reader.read();
+        if (done) break;
+
+        buffer += decoder.decode(value, { stream: true });
+        const lines = buffer.split('\n');
+        buffer = lines.pop() || '';
+
+        for (const line of lines) {
+          if (line.startsWith('data: ')) {
+            const data = line.slice(6);
+            if (data === '[DONE]') {
+              return;
+            }
+
+            try {
+              const parsed = JSON.parse(data);
+              yield parsed;
+            } catch (e) {
+              console.warn('Failed to parse SSE data:', data);
+            }
+          }
+        }
+      }
+    } catch (error: any) {
+      yield { type: 'error', data: error.message || 'Network error' };
+    }
+  }
+
+  async *streamAssist(
+    instruction: string,
+    context: string,
+    authToken: string
+  ): AsyncGenerator<{ type: 'content' | 'error'; data: any }> {
+    try {
+      const response = await apiClient.request('/chat/assist', {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+          'x-user-language': localStorage.getItem('userLanguage') || 'zh',
+        },
+        body: JSON.stringify({ instruction, context }),
+      });
+
+      if (!response.ok) {
+        yield { type: 'error', data: 'Request failed' };
+        return;
+      }
+
+      const reader = response.body?.getReader();
+      if (!reader) return;
+
+      const decoder = new TextDecoder();
+      let buffer = '';
+
+      while (true) {
+        const { done, value } = await reader.read();
+        if (done) break;
+
+        buffer += decoder.decode(value, { stream: true });
+        const lines = buffer.split('\n');
+        buffer = lines.pop() || '';
+
+        for (const line of lines) {
+          if (line.startsWith('data: ')) {
+            const data = line.slice(6);
+            if (data === '[DONE]') return;
+            try {
+              yield JSON.parse(data);
+            } catch (e) { console.warn(e) }
+          }
+        }
+      }
+    } catch (error: any) {
+      yield { type: 'error', data: error.message };
+    }
+  }
+}
+
+export const chatService = new ChatService();