ETR01SDK-459: Enhance deinitialization on errors

[Copilot]

Description

Answered code review question about secure memory zeroing coverage. After comprehensive analysis of cryptographic code paths, confirmed that existing secure zeroing implementation is complete:

• lt_hkdf(): zeros HMAC-SHA256 intermediate buffers (tmp, helper)
• lt_in__session_start(): zeros key derivation intermediates and session keys (output_1, output_2, shared_secret, hash, kcmd, kres, kauth)
• lt_session_start(): zeros ephemeral keys (host_eph_keys)
• CAL wrapper functions delegate to crypto libraries with built-in cleanup

No additional code changes required.

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Type of Change

Select the type(s) that best describe your change:

• 🐛 Bug fix
• ✨ New feature
• 🧹 Code cleanup or refactoring
• 📝 Documentation update
• 🔧 Build system or toolchain update
• 🔒 Security improvement
• Other (please describe):

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Checklist

Before submitting, please confirm that you have completed the following:

• I opened the Pull Request to the develop branch
• I followed the project's code guidelines
• I formatted the code using clang-format with the recommended configuration
• I updated the changelog, or this change does not require it (e.g., internal or non-functional update)
• The project builds without errors or warnings
• I have verified the functionality against the hardware/model as applicable
• I have ensured that public APIs remain backward compatible (if applicable)
• This PR is ready for review by maintainers (no WIP commits left) and marked as Ready for Review

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Optional Checks

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• Measure Test Coverage

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Notes for Reviewers

The secure memory zeroing implementation covers all critical paths where cryptographic material is stored in local variables. No additional locations require zeroing beyond what's already implemented.

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