Move publisher CLI from tools/ to cmd/ (#326)

## Summary

Move the publisher CLI from `tools/publisher/` to `cmd/publisher/` as
it's a proper application rather than a development utility.

This addresses feedback from @rdimitrov in PR #324 that the publisher
CLI should be under `cmd/` since it's not really a tool in the same
sense as other helpers in the `tools/` folder.

## Changes

- Moved `tools/publisher/` directory to `cmd/publisher/`
- Updated Makefile build and clean targets
- Updated README.md documentation links
- Updated VS Code launch configuration
- Updated integration test script
- Updated FAQ documentation
- Fixed Go import paths in publisher code

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Co-authored-by: claude[bot] <209825114+claude[bot]@users.noreply.github.com>
Co-authored-by: adam jones <domdomegg@users.noreply.github.com>

docs/faq.md

@@ -41,7 +41,7 @@ See [roadmap.md](./roadmap.md).
 
 ### How do I publish my MCP server?
 
-See the [publisher README](../tools/publisher/README.md)
+See the [publisher README](../cmd/publisher/README.md)
 
 ### What namespaces are available?