Closes: #941 Feat/template versioning strictly increasing version test

[Chaampion1-1]

Description

This PR enforces that each newly published version number for a template strictly increases over the previous latest_version ($version > latest_version$) in publish_template_version within onchain/contracts/template_versioning/src/lib.rs.# Related Issue

Fixes # 941

Solution Approach

1. Updated publish_template_version to accept an explicit target version: u32 parameter.
2. Implemented the strictly-increasing version validation guard if version == 0 || version <= latest returning VersioningError::InvalidData.
3. Added NatSpec-style doc comments detailing security invariants, parameters, return values, and error conditions.
4. Added comprehensive unit tests in test_versioning.rs verifying that duplicate/lower versions return InvalidData and sequential version increments ($1 \to 2 \to 3$) succeed.
5. Updated integration test invocations in test_template_versioning_payroll_integration.rs.
6. Documented the invariant, API table updates, error codes, and test coverage in docs/template-versioning.md.

Checklist

• I have tested the changes locally
• I have added/updated documentation as needed
• I have reviewed the code and ensured it follows the project guidelines
• I have added necessary tests (unit/integration)
• My changes generate no new warnings/errors
• I have checked for code formatting issues

Screenshots/Recordings