feat(ai): 添加 AI 助手功能支持多模型对话

- 集成 OpenAI 兼容网关和 Ollama 原生 API 接口
- 新增 AI 测试页面支持流式对话和模型切换
- 配置开发环境同源反向代理解决浏览器 CORS 问题
- 添加环境变量配置支持 AI API 和 Ollama 接口设置
- 实现聊天历史记录、中断请求和参数调节功能
- 提供 Nginx 反向代理配置文档用于生产环境部署

src/api/ai/openai.ts

@@ -0,0 +1,173 @@
+import { AI_API_URL } from '@/config/setting';
+
+export type OpenAIRole = 'system' | 'user' | 'assistant' | 'tool';
+
+export interface OpenAIChatMessage {
+  role: OpenAIRole;
+  content: string;
+  name?: string;
+}
+
+export interface OpenAIModel {
+  id: string;
+  object: string;
+  created?: number;
+  owned_by?: string;
+  name?: string;
+}
+
+export interface OpenAIListModelsResponse {
+  data: OpenAIModel[];
+}
+
+export interface OpenAIChatCompletionRequest {
+  model: string;
+  messages: OpenAIChatMessage[];
+  temperature?: number;
+  top_p?: number;
+  max_tokens?: number;
+  stream?: boolean;
+}
+
+export interface OpenAIChatCompletionChoice {
+  index: number;
+  message?: { role: OpenAIRole; content: string };
+  delta?: { role?: OpenAIRole; content?: string };
+  finish_reason?: string | null;
+}
+
+export interface OpenAIChatCompletionResponse {
+  id?: string;
+  object?: string;
+  created?: number;
+  model?: string;
+  choices: OpenAIChatCompletionChoice[];
+}
+
+function getHeaders(apiKey?: string) {
+  const headers: Record<string, string> = {
+    'Content-Type': 'application/json'
+  };
+  if (apiKey) {
+    const trimmed = apiKey.trim();
+    // Accept either raw token or "Bearer xxx".
+    headers.Authorization = /^bearer\s+/i.test(trimmed)
+      ? trimmed
+      : `Bearer ${trimmed}`;
+  }
+  return headers;
+}
+
+function normalizeBaseURL(baseURL: string) {
+  return baseURL.replace(/\/+$/, '');
+}
+
+export async function listModels(opts?: { apiKey?: string; baseURL?: string }) {
+  const baseURL = normalizeBaseURL(opts?.baseURL ?? AI_API_URL);
+  const res = await fetch(`${baseURL}/models`, {
+    method: 'GET',
+    headers: getHeaders(opts?.apiKey)
+  });
+  if (!res.ok) {
+    const text = await res.text().catch(() => '');
+    throw new Error(
+      `listModels failed: ${res.status} ${res.statusText}${text ? ` - ${text}` : ''}`
+    );
+  }
+  return (await res.json()) as OpenAIListModelsResponse;
+}
+
+export async function chatCompletions(
+  body: OpenAIChatCompletionRequest,
+  opts?: { apiKey?: string; baseURL?: string; signal?: AbortSignal }
+) {
+  const baseURL = normalizeBaseURL(opts?.baseURL ?? AI_API_URL);
+  const res = await fetch(`${baseURL}/chat/completions`, {
+    method: 'POST',
+    headers: getHeaders(opts?.apiKey),
+    body: JSON.stringify(body),
+    signal: opts?.signal
+  });
+  if (!res.ok) {
+    const text = await res.text().catch(() => '');
+    throw new Error(
+      `chatCompletions failed: ${res.status} ${res.statusText}${text ? ` - ${text}` : ''}`
+    );
+  }
+  return (await res.json()) as OpenAIChatCompletionResponse;
+}
+
+/**
+ * Stream OpenAI-compatible SSE (`stream: true`) and emit incremental tokens.
+ * Most gateways (Open-WebUI / LiteLLM / Ollama OpenAI proxy) follow:
+ *   data: { choices: [{ delta: { content: "..." } }] }
+ *   data: [DONE]
+ */
+export async function chatCompletionsStream(
+  body: Omit<OpenAIChatCompletionRequest, 'stream'>,
+  opts: {
+    apiKey?: string;
+    baseURL?: string;
+    signal?: AbortSignal;
+    onDelta: (text: string) => void;
+    onDone?: () => void;
+  }
+) {
+  const baseURL = normalizeBaseURL(opts.baseURL ?? AI_API_URL);
+  const res = await fetch(`${baseURL}/chat/completions`, {
+    method: 'POST',
+    headers: getHeaders(opts.apiKey),
+    body: JSON.stringify({ ...body, stream: true }),
+    signal: opts.signal
+  });
+
+  if (!res.ok || !res.body) {
+    const text = await res.text().catch(() => '');
+    throw new Error(
+      `chatCompletionsStream failed: ${res.status} ${res.statusText}${text ? ` - ${text}` : ''}`
+    );
+  }
+
+  const reader = res.body.getReader();
+  const decoder = new TextDecoder('utf-8');
+  let buffer = '';
+
+  while (true) {
+    const { value, done } = await reader.read();
+    if (done) break;
+    buffer += decoder.decode(value, { stream: true });
+
+    // SSE events are separated by blank lines.
+    let idx = buffer.indexOf('\n\n');
+    while (idx !== -1) {
+      const rawEvent = buffer.slice(0, idx);
+      buffer = buffer.slice(idx + 2);
+      idx = buffer.indexOf('\n\n');
+
+      const lines = rawEvent
+        .split('\n')
+        .map((l) => l.trim())
+        .filter(Boolean);
+      for (const line of lines) {
+        if (!line.startsWith('data:')) continue;
+        const data = line.slice(5).trim();
+        if (!data) continue;
+        if (data === '[DONE]') {
+          opts.onDone?.();
+          return;
+        }
+        try {
+          const json = JSON.parse(data) as OpenAIChatCompletionResponse;
+          const delta = json.choices?.[0]?.delta?.content;
+          if (delta) {
+            opts.onDelta(delta);
+          }
+        } catch {
+          // Ignore malformed chunks
+        }
+      }
+    }
+  }
+
+  opts.onDone?.();
+}