v2.7→v2.8 parity: integration test for AppLauncher + version.xml (Maven packages)

[alexeid]

Part of v2.7→v2.8 parity (raised by Remco). Umbrella: #34.

Status

Appears to work, but needs an end-to-end integration test before declaring done.

Current state

• beast-fx/src/main/java/beastfx/app/tools/AppLauncher.java:234–277 reads version.xml from each installed package root and parses <packageapp> / <addonapp> elements.
• beast-base/pom.xml copies version.xml into the beast-base JAR via maven-resources-plugin.
• beast-pkgmgmt/src/main/java/beast/pkgmgmt/BEASTClassLoader.java scans the classpath for version.xml (both JAR-root and META-INF/beast/version.xml) and registers services.

Work

• End-to-end test: install a Maven package that ships an applauncher app, confirm AppLauncher discovers it and the app launches.
• Confirm version.xml from a Maven-installed package (in ~/.beast/2.8/maven-repo/) is picked up the same way as a CBAN-installed .zip package.
• Document for package authors which version.xml location to use.

Acceptance

• Manual or scripted test pass against at least one Maven-installed package with apps.