feat: use FileSystemFileHandle to modify a file on the local filesystem (#965)

## Launch Checklist

<!-- Thanks for the PR! Feel free to add or remove items from the
checklist. -->


 - [x] Briefly describe the changes in this PR.
 - [x] Link to related issues.
- [x] Include before/after visuals or gifs if this PR includes visual
changes.
 - [ ] Write tests for all new functionality.
 - [x] Add an entry to `CHANGELOG.md` under the `## main` section.

## Changes

- This pull request makes use of the FileSystemFileHandle API to modify
a local file. No need to download it - just click save.
- I don't know how to cover this functionality by tests so I need
directions in case test coverage is required.
- The pull request adds
[@types/wicg-file-system-access](https://www.npmjs.com/package/@types/wicg-file-system-access)
as a new dev dependency which I am not really pleased about but can't
think of a way around it.

## Known Limitations

- The used File API is only available in when accessed from https or on
localhost.
- There is no visual indicator that the file has been saved. Previously
the browser showed it as a new download.

## Issue

- https://github.com/maplibre/maputnik/issues/964

## Screenshots

### Menu
<img
src="https://github.com/user-attachments/assets/dfcfc5c2-0019-4857-ba26-224b5598fc11"
/>

### Open modal
<img
src="https://github.com/user-attachments/assets/4e1293e8-16b6-4b86-925b-3bebb49d8ca6"
height="200px" />

### Save modal
<img
src="https://github.com/user-attachments/assets/4f10e2c0-2dd3-4726-a613-30e0406619b0"
height="200px" />

---------

Co-authored-by: Harel M <harel.mazor@gmail.com>

src/locales/ja/translation.json

@@ -29,7 +29,7 @@
   "Map view": "地図画面",
   "Maputnik on GitHub": "GitHubのMaputnik",
   "Open": "開く",
-  "Export": "エクスポート",
+  "Save": "保存",
   "Data Sources": "データソース",
   "Style Settings": "スタイル設定",
   "View": "表示",
@@ -81,16 +81,14 @@
   "Close modal": "モーダルを閉じる",
   "Debug": "デバッグ",
   "Options": "設定",
-  "Export Style": "スタイルをエクスポート",
-  "Download Style": "スタイルをダウンロード",
-  "Download a JSON style to your computer.": "パソコンにJSONスタイルをダウンロードします。",
-  "Download HTML": "HTMLをダウンロード",
+  "Save Style": "スタイルを保存",
+  "Save the JSON style to your computer.": "JSONスタイルをコンピュータに保存します。",
+  "Save as": "名前を付けて保存",
+  "Create HTML": "HTMLを作成",
   "Cancel": "キャンセル",
   "Open Style": "スタイルを開く",
-  "Upload Style": "スタイルをアップロードする",
-  "Upload a JSON style from your computer.": "JSONスタイルをパソコンからアップロードする",
-  "Style file": "スタイルファイル",
-  "Upload": "アップロード",
+  "Open local Style": "ローカルスタイルを開く",
+  "Open a local JSON style from your computer.": "コンピュータからローカルJSONスタイルを開きます。",
   "Load from URL": "URLから読み込む",
   "Load from a URL. Note that the URL must have <1>CORS enabled</1>.": "URLから読み込む。注意: URLは <1>CORSを有効にする</1> 必要があります。",
   "Style URL": "スタイルURL",