ETR01SDK-429: check logic of low level l2 functions buff len checking

[andreondra]

Description

As a part of this PR I went through both API and low-level functions and verified implementation of buffer length checking. I found one place where the check was not implemented. I also enhanced some comments in libtropic_l2.c.

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• 🐛 Bug fix
• ✨ New feature
• 🧹 Code cleanup or refactoring
• 📝 Documentation update
• 🔧 Build system or toolchain update
• 🔒 Security improvement
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[Copilot]

Pull request overview

This PR adds missing buffer length checking to the lt_session_start function and improves comment consistency in libtropic_l2.c by standardizing protocol layer references to use uppercase (L2/L3 instead of l2/l3).

Changes:

• Added response length validation check in lt_session_start to verify the handshake response length matches the expected value
• Standardized comments in libtropic_l2.c to use uppercase L2/L3 notation consistently

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/libtropic.c	Added buffer length check for handshake response in lt_session_start function
src/libtropic_l2.c	Improved comment consistency by standardizing L2/L3 capitalization and clarifying wording

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

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