Build: adopt HauntedPlatform 1.2.0

[remdui]

HauntedPlatform migration

Moved to HauntedPlatform

• Parent and shared build policy upgraded to 1.2.0.
• The exec plugin now inherits Platform's maven.exec.version (3.6.3).

Intentionally local

• FeatureFramework BOM/modules, Paper and Velocity targets, acceptance tests, repositories, distribution metadata, and FeatureFramework-specific compatibility dependencies.

Validation

• ./mvnw clean verify
• ./mvnw dependency:tree
• ./mvnw help:effective-pom
• ./mvnw -Pplatform-acceptance clean verify

Dependency graph

No production dependency graph change. The only tool change is exec-maven-plugin 3.6.2 to the centrally managed 3.6.3.