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

Reviewed-on: #3

frontend/tsconfig.vitest.json

@@ -0,0 +1,8 @@
+{
+  "extends": "./tsconfig.app.json",
+  "exclude": [],
+  "compilerOptions": {
+    "composite": true,
+    "types": ["node", "jsdom"]
+  }
+}