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/components/FileModified.vue

@@ -0,0 +1,22 @@
+<template>
+  <td class="modified right">
+    <time :data-tooltip=tooltip :datetime=datetime>{{ doc.modified }}</time>
+  </td>
+</template>
+
+<script setup lang="ts">
+import type { Document } from '@/repositories/Document'
+import { computed } from 'vue'
+
+const datetime = computed(() =>
+  new Date(1000 * props.doc.mtime).toISOString().replace('.000Z', 'Z')
+)
+
+const tooltip = computed(() =>
+  datetime.value.replace('T', '\n').replace('Z', ' UTC')
+)
+
+const props = defineProps<{
+    doc: Document
+}>()
+</script>