Add PPN dropdown nala tests for DA metadata builder

[JackySun9]

Summary

• Migrate PPN dropdown tests from the centralized nala repo to da-bacom where the block code lives
• Tests follow the existing nala/blocks/<block>/ pattern used by stats, tree-view, event-speakers, etc.
• 14 test cases covering:
  • Functional (TC-001 to TC-005): dropdown values, selection, free text prevention, metadata population, library integration
  • Bug regression (TC-006 to TC-009): empty values, value reset on property switch, add-without-value prevention, complex flow
  • Non-functional (TC-010 to TC-011): DA UI integration, governance/circumvention prevention
  • Edge cases (TC-012 to TC-014): multiple pairs, removal, first-section error

Why move from nala?

Tests for da-bacom blocks should live alongside the code they test. This enables:

• Tests run automatically on PRs that change the block
• Developers see and maintain tests with their code
• No cross-repo coordination needed

Test plan

• Run PPN dropdown tests on DA Live (requires DA authentication)
• Verify tests match the existing nala block test pattern

Made with Cursor

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (stage@352128d). Learn more about missing BASE report.

Additional details and impacted files

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  Misses           ?      399           
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