Add version browser extension

.gitignore

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+.DS_Store
+node_modules/

LICENSE

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+MIT License
+
+Copyright (c) 2026 MarkEdit.app
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# MarkEdit-version-browser
+
+Browse, compare, and restore saved versions of the current document. Local versions can also be deleted.
+
+## Installation
+
+Install this extension from the [MarkEdit Extension Registry](https://markedit-app.github.io/extensions/#markedit-version-browser).
+
+## How to Use
+
+Open **Extensions > Browse Versions** in MarkEdit. Select a saved version to compare it with the current document, then switch between unified and split layouts as needed. Unchanged sections can be expanded directly in the diff.
+
+Local delete operations require confirmation. The browser refreshes automatically after a version is deleted.
+
+## Settings
+
+In [settings.json](https://github.com/MarkEdit-app/MarkEdit/wiki/Customization#advanced-settings), define a settings node named `extension.markeditVersionBrowser`. The default settings are:
+
+```json
+{
+  "extension.markeditVersionBrowser": {
+    "wrapLines": true,
+    "showLineNumbers": true,
+    "diffIndicators": "classic",
+    "lineDiff": "word-alt",
+    "hunkSeparators": "line-info",
+    "expandUnchanged": false,
+    "expansionLineCount": 20
+  }
+}
+```
+
+- `wrapLines`: Wrap long lines instead of scrolling horizontally.
+- `showLineNumbers`: Show line numbers in the diff gutter.
+- `diffIndicators`: Line indicators: `classic`, `bars`, or `none`.
+- `lineDiff`: Changed-text granularity: `word-alt`, `word`, `char`, or `none`.
+- `hunkSeparators`: Hunk separator style: `simple`, `metadata`, `line-info`, or `line-info-basic`.
+- `expandUnchanged`: Expand unchanged sections by default.
+- `expansionLineCount`: Number of unchanged lines to reveal at a time, clamped from 1 to 100.
+
+## Building
+
+```
+yarn install
+yarn test
+yarn build
+```
+
+`yarn build` also deploys the extension to your local MarkEdit installation.