More efficient flat file list format and various UX improvements (#3)

This is a major upgrade with assorted things included.

- Navigation flows improved, search appears in URL history, cleared when navigating to another folder
- More efficient file list format for faster loads
- Efficient updates, never re-send full root another time (except at connection)
- Large number of watching and filelist updates (inotify issues remain)
- File size coloring
- Fixed ZIP generation random glitches (thread race condition)
- Code refactoring, cleanup, typing fixes
- More tests

frontend/src/main.ts

@@ -0,0 +1,25 @@
+import './assets/main.css'
+
+import { createApp } from 'vue'
+import { createPinia } from 'pinia'
+
+import App from './App.vue'
+import router from './router'
+
+import piniaPluginPersistedState from 'pinia-plugin-persistedstate'
+
+import ContextMenu from '@imengyu/vue3-context-menu'
+import '@imengyu/vue3-context-menu/lib/vue3-context-menu.css'
+
+const app = createApp(App)
+app.config.errorHandler = err => {
+  /* handle error */
+  console.log(err)
+}
+
+const pinia = createPinia()
+pinia.use(piniaPluginPersistedState)
+app.use(pinia)
+app.use(router)
+app.use(ContextMenu)
+app.mount('#app')