Add morphir CLI to mise registry

## Summary

Add the morphir CLI to the [mise](https://mise.jdx.dev/) tool registry so users can install with:
```bash
mise install morphir
```

Instead of the current longer form:
```bash
mise install github:finos/morphir-rust@v0.1.0
```

## Steps

### 1. Add to Aqua Registry (Recommended First Step)

The aqua registry is preferred by mise for security features. Submit a PR to:
https://github.com/aquaproj/aqua-registry

Create a file `pkgs/finos/morphir-rust/registry.yaml`:
```yaml
packages:
- type: github_release
repo_owner: finos
repo_name: morphir-rust
asset: morphir-{{.Version}}-{{.Arch}}-{{.OS}}.{{.Format}}
format: tgz
replacements:
darwin: apple-darwin
linux: unknown-linux-gnu
amd64: x86_64
arm64: aarch64
overrides:
- goos: windows
format: zip
asset: morphir-{{.Version}}-{{.Arch}}-pc-windows-msvc.zip
```

### 2. Add to Mise Registry

Once in aqua (or directly using github backend), submit a PR to:
https://github.com/jdx/mise - edit `registry.toml`

Add entry:
```toml
[tools.morphir]
description = "CLI for working with Morphir IR - functional domain modeling and business logic"
backends = ["aqua:finos/morphir-rust", "github:finos/morphir-rust"]
test = ["morphir --version", "morphir {{version}}"]
```

## Requirements Checklist

- [ ] Several stable releases published
- [ ] Consistent release asset naming convention
- [ ] Tool is reasonably popular/well-maintained (FINOS project)
- [ ] Test command works: `morphir --version` outputs version

## Alternative: GitHub Backend Only

If skipping aqua, submit directly to mise with just the github backend:

```toml
[tools.morphir]
description = "CLI for working with Morphir IR - functional domain modeling and business logic"
backends = ["github:finos/morphir-rust"]
test = ["morphir --version", "morphir {{version}}"]
```

## References

- [mise Registry Documentation](https://mise.jdx.dev/registry.html)
- [mise Contributing Guide](https://mise.jdx.dev/contributing.html)
- [mise registry.toml](https://github.com/jdx/mise/blob/main/registry.toml)
- [aqua Registry](https://github.com/aquaproj/aqua-registry)