dsh-metronome: Rhythm Practice Tool

`dsh-metronome` is a locally running metronome practice tool in the DeepSeek Harness (DSH) ecosystem, implemented purely in Node and maintained by the user `uckkk`. It returns instrument practice plans based on parameters through registered tool interfaces. The plugin does not require network access and is suitable for local metronome or instrument training. Installation requires specific dependencies and runs with the permissions of the current process.