✨ Feat: Extend in-app notifications to MCP and skill repository reviews

[Lifeng-Chen]

Notify publishers and reviewers on submit/approve/reject for MCP and skill listings, with listing/review content, navbar deep-links into mcp/skill space, and shared apply/review modals aligned with agent repository.

[Lifeng-Chen]

SKILL MCP仓库审核增加通知。

[codecov]

Codecov Report

❌ Patch coverage is 74.61538% with 33 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
backend/services/data_process_service.py	77.04%	10 Missing and 4 partials ⚠️
backend/consts/model.py	61.90%	8 Missing ⚠️
backend/database/market_mcp_db.py	0.00%	2 Missing and 2 partials ⚠️
backend/services/skill_repository_service.py	78.57%	0 Missing and 3 partials ⚠️
backend/database/skill_repository_db.py	0.00%	1 Missing and 1 partial ⚠️
backend/services/mcp_management_service.py	92.30%	1 Missing and 1 partial ⚠️

📢 Thoughts on this report? Let us know!