Migrate official MCP SDK logging from Logrus to slog

[glbyktjys]

This PR:

• Initializes a dedicated slog logger when the official MCP server starts in HTTP mode.
• Passes the logger to the official SDK for server and session logging.
• Updates the tool-logging middleware to record successful calls, protocol errors, and tool execution errors using structured slog records.
• Writes official SDK logs to terraform-mcp-official.log, keeping them isolated from the existing Logrus output.

What hasn’t changed:

• Stdio logging remains on Logrus.
• Shared HTTP wrappers continue using Logrus to preserve the existing server behavior.
• Official client initialization remains on Logrus and will be migrated after the HTTP client and session-management changes are complete.

PCI review checklist

• I have documented a clear reason for, and description of, the change I am making.

• If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.

• If applicable, I've documented the impact of any changes to security controls.

  Examples of changes to security controls include using new access control methods, adding or removing logging pipelines, etc.

[Shweta-Deshpande]

I see the defensive check on logger != nil was removed here. Do we not need it anymore?

[glbyktjys]

Thanks for catching that! I missed preserving the nil guard while expanding the logging logic. I’ll restore it so the middleware continues without logging if the logger is nil.

[Shweta-Deshpande]

Should this const be renamed to officialSlogOutputFileName instead of Path? I'm just wondering where it tries to look for this file in initSlog. Is it in the cwd?

[glbyktjys]

Agreed the new name would be clearer. It’s a relative filename, so the log is created in the cwd. If the server restarts from the same directory, it appends to the existing file. I’ll rename it accordingly.