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

---------

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

.vscode/launch.json

@@ -18,10 +18,10 @@
             "type": "go",
             "request": "launch",
             "mode": "auto",
-            "program": "${workspaceFolder}/tools/publisher/main.go",
+            "program": "${workspaceFolder}/cmd/publisher/main.go",
             "args": [
                 "-registry-url=http://localhost:8080",
-                "-mcp-file=${workspaceFolder}/tools/publisher/server.json",
+                "-mcp-file=${workspaceFolder}/cmd/publisher/server.json",
             ],
         }
     ]