Fix Deploy Snapshots: add -SNAPSHOT suffix to version 0.2.2

[Copilot]

The "Deploy Snapshots" CI job was failing with 401 on https://repo.embabel.com/artifactory/libs-release because version 0.2.2 (non-SNAPSHOT) caused Maven to route deployment to the releases repository instead of snapshots. The EMBABEL_ARTIFACTORY credentials only have write access to the snapshots repo.

Changes

• Version fix: 0.2.2 → 0.2.2-SNAPSHOT in all four pom.xml files (parent + 3 submodules), restoring Maven's routing to embabel-snapshots
• Incorporates 2.0.0 branch changes: Cherry-picked the "Boot 4.1 stream upgrade" commit (new parent POM com.embabel.build:embabel-build-parent:2.0.0-SNAPSHOT, updated embabel-common and embabel-agent versions to 2.0.0-SNAPSHOT)
• Gitignore cleanup: Added *.versionsBackup to .gitignore and removed Maven version plugin backup files that were accidentally committed

<!-- Before -->
<version>0.2.2</version>   <!-- routes to libs-release → 401 -->

<!-- After -->
<version>0.2.2-SNAPSHOT</version>   <!-- routes to libs-snapshot → succeeds -->