Make `mcp-publisher init` copy `version` from `package.json`

[jonathanhefner]

Currently, mcp-publisher init copies information from package.json, if available. However, it does not copy version for either the top-level server version field nor the packages[].version field in server.json.

The recommended best practice is for server version to align with package version:

https://github.com/modelcontextprotocol/registry/blob/18cde88a7e1c7916f1433c1f131a8de2fec8fe65/docs/explanations/versioning.md#L26-L38

Therefore, mcp-publisher init should copy version from package.json to both version fields in server.json.