Add unit tests for template compatibility parsing and edge cases

[Nanle-code]

Add focused unit tests for template semver parsing, check_version_range, and compatibility edge cases such as missing version bounds, malformed version strings, and out-of-range CLI versions. This improves the robustness of template compatibility logic.

[Pidoko257]

@Pidoko257 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

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[drips-wave]

Congratulations, @Pidoko257! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @Pidoko257: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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