publish subcommand's --file flag not working #767

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. place the server.json in .registry/server.json.
2. Run mcp-publisher publish --file .registry/server.json --dry-run
3. Error Error: server.json not found. Run 'mcp-publisher init' to create one

Expected behavior
A clear and concise description of what you expected to happen.

Expected dry run to run on the .registry/server.json file.

Logs
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Here's the error message:
Error: server.json not found. Run 'mcp-publisher init' to create one

Additional context
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