`.mcpregistry_*` token files should be stored in a unified folder ignored from git

[vemonet]

Is your feature request related to a problem? Please describe.

When using mcp-publisher login it generates multiples .mcpregistry_* files in the root of my project, e.g. .mcpregistry_github_token, .mcpregistry_registry_token

To avoid commiting them I need to manually add .mcpregistry_* to my .gitignore, this is not ideal and there are more elegant and safer ways to handle this situation

Describe the solution you'd like

• Create a .mcpregistry/ folder for all files (tokens, etc) related to the MCP publisher (naming at your convenience)
• Add a .mcpregistry/.gitignore file containing * to automatically ignore the whole folder