fix(installer): map a stacked hotfix stamp to a file version

[coreybutler]

Summary

• Inno Setup maps 2.0.2-2.0.1-hotfix.1 to file version 2.0.2.1. 2.0.2 stays 2.0.2.0, and 2.0.1-hotfix.1 stays 2.0.1.1.
• The Community Release form replaces the free-text prerelease stamp with a kind dropdown: none, alpha, beta, rc, or hotfix.
• Fill in Prerelease number for every kind except none. Fill in Hotfix base only for hotfix (for example 2.0.1). Leave Hotfix base empty to use the latest non-prerelease GitHub release.
• alpha, beta, and rc stamp the manifest (2.0.2-beta.1). hotfix stamps the prior stable version (2.0.1-hotfix.1).

Test plan

• Merge, then open Run workflow and confirm the three new fields and their descriptions
• none with an empty number publishes the manifest version
• beta and number 1 publishes {manifest}-beta.1
• hotfix, number 1, empty base publishes {latest-stable}-hotfix.1
• hotfix and base 2.0.1 publishes 2.0.1-hotfix.1