cherry-pick: Add tag value API endpoints and related functionality

[mdolina]

• Add tag value API endpoints and related functionality

[coolwater]

PR Summary:
Cherry-picks tag value API enhancements into the main branch, introducing support for tag values alongside existing tag retrieval. Changes include:

• Adds TagValue constant to support value-based tagging.
• Introduces new API handler GetTagsWithValuesByMemberHandler to fetch tags with associated values.
• Improves existing GetTagsByMemberHandler with proper error handling and response marshalling.
• Ensures consistent error handling and response formatting across tagging APIs.
• Updates relevant handlers and wiring to enable tag + value retrieval functionality.

Approval Note:
Looks good — clean cherry-pick with focused changes, improved error handling, and clear extension for tag value support. Safe to merge.