Make release automation validate existing tags and releases before publish

[postigodev]

Summary

The current PowerShell release flow already automates version sync, Tauri build, and GitHub release creation, but it should be more defensive around tag/release state.

Why this matters

We already hit a case where a local tag conflicted with GitHub release creation.

Expected outcome

Before publish, the script should validate things like:

• target tag already exists locally
• target tag already exists remotely
• release already exists on GitHub
• repo has uncommitted changes that would make the release inconsistent

Likely files

• release.ps1