Restore unspecified enum wire values

[tejaskochar-db]

Summary

Fixes existing *_UNSPECIFIED enum constants so they use the values declared by the API instead of the empty string. No enum constants are removed.

This supersedes #270, which introduced the empty-string mapping.

Why

The empty-string mapping changed the serialized value of these constants and broke compatibility with APIs that expect their declared enum strings. This fix keeps the existing TypeScript constants and restores the wire values they represent.

Whether these constants should be removed from the public API is intentionally deferred to a separate decision.

What changed

Interface changes

• No constants were added or removed.

Behavioral changes

• Fixed the declared string values of 202 existing *_UNSPECIFIED constants across 49 packages.
• Serializing an affected constant now sends its declared *_UNSPECIFIED string instead of an empty string.

Internal changes

• Regenerated the affected model files.
• Added a bug-fix changelog entry to every affected package.

How is this tested?

npm run ci passes, including builds, linting, formatting checks, type checking, Node tests, browser tests, and license validation.