Add multi-module Maven support

[adityankale190895]

Adds an initial native Maven/Java adapter for multi-module reactors.

• discovers Java sources/tests per Maven module
• models inter-module dependencies from POM coordinates
• propagates source changes into downstream module tests
• recognizes conventional Surefire test names
• emits mvn -pl <modules> -am test for selective execution
• treats POM changes conservatively as configuration changes
• adds a two-module library -> application regression test

This is intentionally an MVP: profiles, plugin-specific test layouts, Failsafe integration-test conventions, generated sources, and non-standard source directories should remain conservative follow-up work.