Feature: dist command handlers + resolver plumbing

**Summary**
Implement `morphir dist` commands with global-first + `--local` override, using resolver plumbing from the design.

**Scope**
- Commands: `dist list|install|use|remove|which [--platform ...] [--local]`.
- Path resolution per design (global preferred; local when `--local`).
- Persist active selection (global vs local) via layered config.
- Happy-path install/use/remove/list/which for at least one platform.
- Logging to stderr; stdout for command data.
- JSONC manifest read/write.

**Acceptance**
- Commands function for one platform end-to-end.
- Resolution precedence matches design.
- Tests for handlers and path resolution (global vs local).
- Basic docs snippet for dist commands.