Add micro.mu configuration for enhanced micro run

[asim]

Summary

Adds a micro.mu configuration file to enable the enhanced micro run experience from go-micro PR #2829.

Configuration

service users
    path ./users
    port 8081

service posts
    path ./posts
    port 8082
    depends users

service comments
    path ./comments
    port 8083
    depends users posts

service web
    path ./web
    port 8089
    depends users posts comments

env development
    GIN_MODE debug
    STORE_ADDRESS file://./data

env production
    GIN_MODE release

Benefits

1. Hot reload - Change code, services auto-rebuild and restart
2. Dependency ordering - Services start in correct order (users first, web last)
3. Environment management - micro run --env production
4. Self-documenting - Configuration shows service relationships

Usage

# Development with hot reload
micro run

# Production mode
micro run --env production

# Without hot reload
micro run --no-watch

Dependencies

Requires go-micro v5 with micro/go-micro#2829