Fix build that broke with 77 removal and make sync curation + build more robust

[dessertplanet]

This pull request updates the curation workflow for program cards to automatically remove empty assignments for deleted cards, while ensuring that assignments with editorial flairs are preserved for manual review. It updates documentation, validation logic, synchronization behavior, and PR rule checks to reflect these changes, and adds new tests to verify the revised logic.

Curation workflow improvements:

• The synchronization process now removes empty assignments for deleted cards, but retains assignments that have editorial flairs, requiring manual investigation before deletion. [1] [2] [3] [4] [5]
• Validation distinguishes between stale empty assignments (now just a warning) and stale assignments with flairs (still an error). [1] [2]

Documentation updates:

• The curation documentation has been revised to explain the new behavior for handling empty and assigned stale entries, clarifying safe editing rules and workflow steps. [1] [2] [3]

PR rules and automation:

• The PR rule logic for allowing synchronized changes to flairs.yml now supports both adding missing empty assignments and removing empty assignments for deleted cards, and tests have been added to verify this. [1] [2]

Codebase and test enhancements:

• The validate and synchronize functions are now exported for testing, and new tests cover the updated validation and synchronization logic. [1] [2]
• The nanoid dependency is updated from version 3.3.16 to 3.3.18.

Curation data update:

• A stale empty assignment (77_Placeholder) was removed from flairs.yml.

[github-actions]

⚠️ Program card PR validation succeeded with warnings

PR validation is intended for maintainers, not card authors. If you're a card author and don't understand this report, don't worry about it!

0 info.yaml file(s) checked · 0 error(s) · 7 warning(s)

Triggered by:

• M documentation/curating-program-card-index.md
• M tools/sitegen/package-lock.json
• M tools/sitegen/src/curation/cli.js
• M tools/sitegen/src/curation/flairs.yml
• M tools/sitegen/src/validate/prRules.js
• A tools/sitegen/test/curation-cli.test.js
• M tools/sitegen/test/pr-rules.test.js

No info.yaml file was added or modified.

Other rules

Severity	Affected path	Rule	Message
⚠️ Warning	documentation/curating-program-card-index.md	change-outside-release-directory	Card submissions must not include changes outside releases/<card>/ directories.
⚠️ Warning	tools/sitegen/package-lock.json	change-outside-release-directory	Card submissions must not include changes outside releases/<card>/ directories.
⚠️ Warning	tools/sitegen/src/curation/cli.js	change-outside-release-directory	Card submissions must not include changes outside releases/<card>/ directories.
⚠️ Warning	tools/sitegen/src/curation/flairs.yml	change-outside-release-directory	Card submissions must not include changes outside releases/<card>/ directories.
⚠️ Warning	tools/sitegen/src/validate/prRules.js	change-outside-release-directory	Card submissions must not include changes outside releases/<card>/ directories.
⚠️ Warning	tools/sitegen/test/curation-cli.test.js	change-outside-release-directory	Card submissions must not include changes outside releases/<card>/ directories.
⚠️ Warning	tools/sitegen/test/pr-rules.test.js	change-outside-release-directory	Card submissions must not include changes outside releases/<card>/ directories.