refactor: extract Electron shell to apps/desktop/

Move Electron-specific code (main, preload, shared) and configs
(electron.vite, electron-builder) into apps/desktop/ to prepare
for multi-platform support (Web Browser standalone).

- Create apps/desktop/ with dedicated package.json and tsconfig
- Split Electron deps (electron, electron-updater, better-sqlite3,
  etc.) from shared frontend deps in root package.json
- Declare better-sqlite3 and @node-rs/jieba in packages/node-runtime
- Add stream-json to packages/parser where it belongs
- Update all path aliases (@electron/* → apps/desktop/*) in tsconfig,
  vite configs, and relative imports in preload/main
- Keep slim root tsconfig.node.json as shared base for packages
- Update CI/CD release workflow for new directory layout
- Fix pre-existing type errors (pi-ai Model generic, SQLLabTab
  LLMChatStreamChunk, filter.test.ts empty methods)

apps/desktop/preload/index.ts

@@ -0,0 +1,81 @@
+/**
+ * Electron Preload Script
+ * 将主进程 API 暴露给渲染进程
+ */
+import { contextBridge } from 'electron'
+import { electronAPI } from '@electron-toolkit/preload'
+
+// 从拆分的模块导入 API
+import { extendedApi } from './apis/core'
+import { chatApi, mergeApi } from './apis/chat'
+import { aiApi, llmApi, agentApi, assistantApi, skillApi } from './apis/ai'
+import { nlpApi, networkApi, cacheApi, sessionApi } from './apis/utils'
+import { apiServerApi } from './apis/api-server'
+
+// 为渲染进程提供统一的类型入口，避免 type-only import 指向无导出的运行时代码。
+export type { PreprocessConfig } from './apis/ai'
+export type {
+  ProviderDefinition,
+  ProviderKind,
+  ModelDefinition,
+  ModelCapability,
+  ModelStatus,
+  ModelRecommendedFor,
+  LLMConnectionConfig,
+  LLMConnectionConfigCompat,
+  ModelUsage,
+  ModelSelectionState,
+} from '../main/ai/llm/model-types'
+
+// Use `contextBridge` APIs to expose Electron APIs to
+// renderer only if context isolation is enabled, otherwise
+// just add to the DOM global.
+if (process.contextIsolated) {
+  try {
+    contextBridge.exposeInMainWorld('electron', electronAPI)
+    contextBridge.exposeInMainWorld('api', extendedApi)
+    contextBridge.exposeInMainWorld('chatApi', chatApi)
+    contextBridge.exposeInMainWorld('mergeApi', mergeApi)
+    contextBridge.exposeInMainWorld('aiApi', aiApi)
+    contextBridge.exposeInMainWorld('llmApi', llmApi)
+    contextBridge.exposeInMainWorld('agentApi', agentApi)
+    contextBridge.exposeInMainWorld('assistantApi', assistantApi)
+    contextBridge.exposeInMainWorld('skillApi', skillApi)
+    contextBridge.exposeInMainWorld('cacheApi', cacheApi)
+    contextBridge.exposeInMainWorld('networkApi', networkApi)
+    contextBridge.exposeInMainWorld('sessionApi', sessionApi)
+    contextBridge.exposeInMainWorld('nlpApi', nlpApi)
+    contextBridge.exposeInMainWorld('apiServerApi', apiServerApi)
+  } catch (error) {
+    console.error(error)
+  }
+} else {
+  // @ts-ignore (define in dts)
+  window.electron = electronAPI
+  // @ts-ignore (define in dts)
+  window.api = extendedApi
+  // @ts-ignore (define in dts)
+  window.chatApi = chatApi
+  // @ts-ignore (define in dts)
+  window.mergeApi = mergeApi
+  // @ts-ignore (define in dts)
+  window.aiApi = aiApi
+  // @ts-ignore (define in dts)
+  window.llmApi = llmApi
+  // @ts-ignore (define in dts)
+  window.agentApi = agentApi
+  // @ts-ignore (define in dts)
+  window.assistantApi = assistantApi
+  // @ts-ignore (define in dts)
+  window.skillApi = skillApi
+  // @ts-ignore (define in dts)
+  window.cacheApi = cacheApi
+  // @ts-ignore (define in dts)
+  window.networkApi = networkApi
+  // @ts-ignore (define in dts)
+  window.sessionApi = sessionApi
+  // @ts-ignore (define in dts)
+  window.nlpApi = nlpApi
+  // @ts-ignore (define in dts)
+  window.apiServerApi = apiServerApi
+}