Refactor: Replace String Tags with Structured Tag Objects Across Backend, Database, and UI

[rakdutta]

This pull request closes issue #1442 and introduces a richer, structured tag system across the entire MCP Context Forge application. Previously, tags were stored and handled as plain strings. They are now represented as objects/dictionaries containing both an id and a label, enabling future extensibility and more consistent filtering and display.

Database migration and model changes:

• Added Alembic migration 9e028ecf59c4_tag_records_changes_list_str_to_list_ to convert all tags columns in key tables from lists of strings to lists of dicts with id and label fields, and provides a downgrade path to revert the change.
• Updated all relevant Pydantic models in mcpgateway/schemas.py (ToolRead, ResourceRead, PromptRead, GatewayRead, ServerRead, A2AAgentRead, GrpcServiceRead) so their tags field is now a list of dictionaries instead of a list of strings. [1] [2] [3] [4] [5] [6] [7]

Backend logic updates:

• Updated tag filtering logic in mcpgateway/services/export_service.py to match by tag id when tags are dictionaries, ensuring consistent filtering regardless of tag format.
• Modified resource conversion and tool creation logic to handle the new tag format, normalizing tags to human-readable labels where needed. [1] [2] [3]

Frontend and template updates:

• Updated all admin panel JavaScript functions in mcpgateway/static/admin.js to correctly display and edit tags, showing tag labels (or ids) when tags are objects and maintaining compatibility with string tags. [1] [2] [3] [4] [5] [6] [7] [8]
• Updated templates in mcpgateway/templates/admin.html to display tag ids when tags are dictionaries, ensuring consistent rendering in the UI. [1] [2]