[WIP] Add edge case testing for Publish-SFACertificates

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

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This section details on the original issue you should resolve

<issue_title>🧪 Add edge case testing for Publish-SFACertificates</issue_title>
<issue_description>## Overview
Expand Pester test coverage for Phase 4 (Edge Cases) of issue #50 to ensure Publish-SFACertificates handles unusual scenarios gracefully.

Edge Cases to Test

• Test with expired certificates
• Test with special characters in certificate names (spaces, dashes, parentheses, etc.)
• Test archive folder filtering with various folder structures
• Test with very long filenames (approaching Windows path limits)
• Test with mixed case branch codes (JBa vs JBA)
• Test with missing or malformed branch mapping entries
• Test with duplicate certificate names across branches

Implementation Details

Add new test contexts to Tests/SFA/Publish-SFACertificates.Tests.ps1:

1. Create temporary test certificates with edge case names
2. Mock certificate store operations where needed
3. Validate that script handles these cases without throwing unexpected errors
4. Ensure report generation captures edge case scenarios

Acceptance Criteria

• All edge case tests pass with Pester 5.7.1
• Test coverage includes at least 5 of the 7 scenarios listed above
• Tests are repeatable and don't require external dependencies
• Documentation in test file explains each edge case and expected behavior

Related Issue

Resolves Phase 4 of #50: Debug SFA Certificate Distribution Issues</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes 🧪 Add edge case testing for Publish-SFACertificates #61

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