Improve CLI UX and unify local config under ~/.menlo

[LazyYuuki]

Summary

• replace version subcommand with flags (menlo --version and menlo -V) and remove menlo version
• fix first-run config handling so missing config no longer breaks menlo init/menlo config apikey
• remove duplicate default robot configuration path (menlo config default-robot) in favor of menlo robot connect
• improve menlo robot session output labels and formatting for copy/paste
• re-enable robot movement actions via menlo robot action
• move CLI state/config home to ~/.menlo and update installer/uninstaller/docs to match

Testing

• go build -o menlo ./cmd/menlo
• go test -v ./...
• manually verified:
  • ./menlo --version and ./menlo -V
  • ./menlo config --help
  • ./menlo robot --help includes action
  • first-run config write flow under ~/.menlo/config.yaml