Use assembly version for update version display

[siewers]

Summary

• Use Assembly.GetName().Version.ToString(3) with v prefix instead of informational version
• Output now matches tag format exactly (e.g. v0.2.1 instead of 0.2.1+hash)

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
NetatmoTrueTempSync	1%	3%	1514	❌
Summary	1% (41 / 3736)	3% (37 / 1433)	1514	❌