feat: add TypeScript definition

[malept]

• I have read the contribution documentation for this project.
• I agree to follow the code of conduct that this project follows, as appropriate.
• The changes are appropriately documented (if applicable).
• The changes have sufficient test coverage (if applicable).
• The testsuite passes successfully on my local machine (if applicable).

Summarize your changes:

Based on @types/electron-packager, it's updated for 14.2.1. It replaces docs/api.md as the canonical API documentation (docs/api.md remains with a link-based redirect for links to the Markdown file).

I've tested this definition with Electron Forge locally.

Additionally, this adds a GitHub Action to build the docs for master & tags, and publishes them to GitHub Pages.

[codecov]

Codecov Report

Merging #1131 into master will not change coverage by %.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #1131   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           14        14           
  Lines          712       712           
=========================================
  Hits           712       712           

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