Add README coverage badge and PR coverage checks

Run the PR test workflow through npm run test:coverage and add a
coverage badge in README so coverage status is visible from the
repository page.

Add c8 as a dev dependency and ignore generated .coverage/ and
coverage/ artifacts to keep local coverage output out of commits.

Normalize the c8 --include glob quoting in package.json so the pattern
is parsed as intended during script execution.

Co-authored-by: kiloconnect[bot] <240665456+kiloconnect[bot]@users.noreply.github.com>

Author: PeterDaveHello

.github/workflows/pr-tests.yml

@@ -34,6 +34,6 @@ jobs:
         with:
           node-version: 22
       - run: npm ci
-      - run: npm test
+      - run: npm run test:coverage
       - run: npm run lint
       - run: npm run build

.gitignore

@@ -2,5 +2,7 @@
 .vscode/
 node_modules/
 build/
+.coverage/
+coverage/
 .DS_Store
 *.zip

README.md

@@ -12,6 +12,7 @@ Deep ChatGPT integrations in your browser, completely for free.
 [![release][release-image]][release-url]
 [![size](https://img.shields.io/badge/minified%20size-390%20kB-blue)][release-url]
 [![verfiy][verify-image]][verify-url]
+[![coverage][coverage-image]][coverage-url]
 
 English   |   [Indonesia](README_IN.md)   |   [简体中文](README_ZH.md)   |   [日本語](README_JA.md)   |   [Türkçe](README_TR.md)
 
@@ -40,6 +41,10 @@ English   |   [Indonesia](README_IN.md)   | &
 
 [verify-url]: https://github.com/ChatGPTBox-dev/chatGPTBox/actions/workflows/verify-configs.yml
 
+[coverage-image]: https://github.com/ChatGPTBox-dev/chatGPTBox/workflows/pr-tests/badge.svg
+
+[coverage-url]: https://github.com/ChatGPTBox-dev/chatGPTBox/actions/workflows/pr-tests.yml
+
 [Chrome-image]: https://img.shields.io/badge/-Chrome-brightgreen?logo=google-chrome&logoColor=white
 
 [Chrome-url]: https://chrome.google.com/webstore/detail/chatgptbox/eobbhoofkanlmddnplfhnmkfbnlhpbbo