Address feedback on release process improvements for error handling and race conditions

[Copilot]

Description

Addresses review feedback from #427 regarding race condition detection and error messaging in the release workflow.

Changes:

• Early race condition validation: Added pre-build step that checks for conflicts before the long Maven build:

  • Detects if tag was re-created on remote after deletion (via git ls-remote)
  • Detects if branch has new commits since workflow started
  • Fails fast with actionable error message

• Improved error messaging: Updated push step failures to explain:

  • Root cause (likely race condition from POM changes merged during build)
  • Resolution path (delete draft release, create new one via GitHub UI)
  • Whether artifacts were deployed to Maven Central

• Tag existence handling (already in f6d0210): Step now exits with error (exit 1) when tag exists pointing to wrong commit, rather than silently succeeding

Resolves feedback from:

• Add Automated Release workflow: prepare/perform Maven releases and publish draft releases #427 (comment)
• Add Automated Release workflow: prepare/perform Maven releases and publish draft releases #427 (comment)
• Add Automated Release workflow: prepare/perform Maven releases and publish draft releases #427 (comment)

Checklist:

• Public methods are documented
• Public methods are tested
• New and existing tests pass when run locally
• There are no new warnings or errors

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