Upgrade java build

[yuzawa-san]

Issue #, if available: none

Description of changes:

hello kevin, i'm glad we're on github now

• this pr is in preparation for a subsequent pr related to maven publication
• manage version, name, and group in a cleaner manner (e.g. version in gradle.properties). feel free to suggest a different naming scheme
• remove broken dependency to lib
• make it compile on jdk 25, upgrade gradle and various plugins to work on that version
• add rudimentary github actions build job for PR's
• convert enforcedPlatform to platform to work with maven uploads
• add gitignore

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