More config overwrite request

[netcookies]

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1. Need more config overwrite
2. option to select systemctl —user or systemctl (some linux distribution don’t have systemctl —user)

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[chrisis58]

We share the same request for more config overwriting, and I took a shot at implementing this on my own fork. Feel free to check it out if you're interested and see what you think.

The code is here: [dev branch on chrisis58/mihoro](https://github.com/chrisis58/mihoro/tree/dev)

Here's My Idea

Simply put, it's a three-tiered priority system for configs:

mihoro.toml > base.yaml > remote config.yaml

1. Remote config.yaml: This is the bottom layer, coming from your subscription URL. It has the lowest priority.
2. base.yaml: This is a new, optional file you can place in ~/.config/mihomo/. You can put your own custom configs here.
3. mihoro.toml: This layer stays the same. It's for the most common settings has the highest priority.

How It Works

I've added a new option in mihoro.toml called base_config_path, which defaults to ~/.config/mihomo/base.yaml.

When you run mihoro, the program will:

1. Fetch the remote config first.
2. Then, merge your base.yaml on top of it.
3. Finally, apply the overrides from your mihoro.toml.

The merge logic appends them instead of replacing the whole list.

base.yaml Example:

# ~/.config/mihomo/base.yaml

# values like 'dns' will completely replace the remote config's block.
dns:
  enable: true
  listen: 0.0.0.0:53

# lists like 'nameserver' will be appended to the remote list.
nameserver:
  - 8.8.8.8
  - 1.1.1.1

# the rules list is also appended.
rules:
  - DOMAIN-SUFFIX,my-company.com,DIRECT

How to Try It Out

Since this isn't an official release, you'll need to build it from the source:

1. Prerequisites: Make sure you have a Rust environment set up ([rustup.rs](https://rustup.rs/)).

2. Clone and switch to the dev branch:

   git clone [https://github.com/chrisis58/mihoro.git](https://github.com/chrisis58/mihoro.git)
   cd mihoro
   git checkout dev
   

3. Compile and install:

   cargo install --path .
   

   This command will install the compiled mihoro binary to ~/.cargo/bin/. Remember to make sure this directory is in your $PATH.

Reminder

I haven't added an auto-validation feature yet. So, after you edit your base.yaml, I strongly recommend manually running mihomo's built-in command to check if your config file is valid:

mihomo -t -f <base_config>