[EhsanCreator]

Summary

• Fix PowerShell hashtable parse failure caused by case-insensitive duplicate proxy environment keys.
• Snapshot canonical proxy variables and restore them in the launcher finally block.
• Add regression coverage for PowerShell hashtable key collisions and AST parsing of packaged scripts.

Verification

• GitHub Actions run #42809777110 completed successfully across Ubuntu/Windows with Node 22/24.
• Windows jobs passed launcher build, packaging checks, PowerShell AST parsing, and release verification.

Closes the Windows launcher hotfix reported against main.