fix(shorebird_cli): select correct arch for local engine target

[bryanoltman]

Description

Updates availableAndroidArchs to match on exact engine path. This fixes an issue where --target-platform=android-arm64 would incorrectly match android-arm (i.e., arm32) and return the wrong architecture, causing the release command to fail.

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (ad3be55) to head (43b40d0).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1963   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          177       177           
  Lines         5560      5560           
=========================================
  Hits          5560      5560           

Flag	Coverage Δ
shorebird_cli	100.00% <100.00%> (ø)

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