Tidy up frontend directory tree

frontend/src/App.tsx

@@ -1,6 +1,6 @@
 import React from 'react';
 import './App.css';
-import { Waveform } from './Waveform';
+import { Waveform } from './Waveform/Waveform';
 
 const audioContext = new AudioContext();
 

frontend/src/Waveform/Canvas.tsx

@@ -1,5 +1,5 @@
 import { useEffect, useRef } from 'react';
-import { CanvasLogicalWidth, CanvasLogicalHeight } from '../Waveform';
+import { CanvasLogicalWidth, CanvasLogicalHeight } from './Waveform';
 
 const maxPeakValue = 32_768;
 

frontend/src/Waveform/Helpers.tsx

@@ -1,4 +1,4 @@
-import { CanvasLogicalWidth } from '../Waveform';
+import { CanvasLogicalWidth } from './Waveform';
 import { MouseEvent } from 'react';
 
 // TODO: add tests

frontend/src/Waveform/Overview.tsx

@@ -1,10 +1,6 @@
 import { useEffect, useState, useRef, MouseEvent } from 'react';
 import { Canvas as WaveformCanvas } from './Canvas';
-import {
-  CanvasLogicalWidth,
-  CanvasLogicalHeight,
-  Selection,
-} from '../Waveform';
+import { CanvasLogicalWidth, CanvasLogicalHeight, Selection } from './Waveform';
 import { mouseEventToCanvasX } from './Helpers';
 
 interface Props {

frontend/src/Waveform/Thumbnails.tsx

@@ -1,5 +1,5 @@
 import { useState, useEffect, useRef } from 'react';
-import { CanvasLogicalWidth, CanvasLogicalHeight, MediaSet } from '../Waveform';
+import { CanvasLogicalWidth, CanvasLogicalHeight, MediaSet } from './Waveform';
 
 interface Props {
   mediaSet: MediaSet;

frontend/src/Waveform/Waveform.tsx

@@ -1,8 +1,8 @@
 import { useEffect, useState, useRef, MouseEvent } from 'react';
-import { Waveform as WaveformOverview } from './Waveform/Overview';
-import { Thumbnails } from './Waveform/Thumbnails';
-import { Canvas as WaveformCanvas } from './Waveform/Canvas';
-import { canvasXToFrame, mouseEventToCanvasX } from './Waveform/Helpers';
+import { Waveform as WaveformOverview } from './Overview';
+import { Thumbnails } from './Thumbnails';
+import { Canvas as WaveformCanvas } from './Canvas';
+import { canvasXToFrame, mouseEventToCanvasX } from './Helpers';
 
 interface Props {
   audioContext: AudioContext;