fix(conf_env): enhance environment variable loading for config

[qwqcode]

New Environment Variable documentation is published: https://artalk.js.org/guide/env.html

This PR includes:

• Adding a mapping from environment variable names to configuration node paths by reading golang struct tags via reflect

  • Supports setting array variables using numeric index and space separators

• Adding a configuration documentation generator

  • Parses YAML template configuration file comments to automatically generate environment variable documentation

• Structured configuration file option metadata

  type OptionsMeta struct {
      Title      string   `json:"title" yaml:"title"`
      Desc       string   `json:"desc" yaml:"desc"`
      Type       string   `json:"type" yaml:"type"`
      Options    []string `json:"options" yaml:"options"`
      Env        string   `json:"env" yaml:"env"`
      Path       string   `json:"path" yaml:"path"`
      PathText   string   `json:"path_title" yaml:"path_title"`
      Default    any      `json:"default" yaml:"default"`
      IsRoot     bool     `json:"is_root" yaml:"is_root"`
      HasChild   bool     `json:"has_child" yaml:"has_child"`
      AllowsSet  bool     `json:"allows_edit" yaml:"allows_edit"`
      CommentRaw string   `json:"comment_raw" yaml:"comment_raw"`
  }

• Optimizing deployment documentation

• Solving the problem of configuring the frontend interface through environment variables

• Implemented GetOptionsMetaData, GetEnvPathMapByModel, Unflatten functions

• Improved numerous unit tests

related to #559 #573 #790 (comment)

fixes #875

---

Next optimization steps:

Hardcode the output results of GetOptionsMetaData into the code and generate them using go generate. This will avoid repeating the YAML configuration file parsing and reading reflect tags to obtain the confNodePaths => envName mapping table every time Artalk starts. (This has been implemented in 401cf5c)

[codecov]

Codecov Report

Attention: Patch coverage is 74.27885% with 107 lines in your changes are missing coverage. Please review.

Project coverage is 29.60%. Comparing base (d2161cc) to head (cbfc880).
Report is 1 commits behind head on master.

Files	Patch %	Lines
internal/config/meta/gen/main.go	0.00%	86 Missing ⚠️
internal/config/env_provider/provider.go	91.58%	6 Missing and 3 partials ⚠️
internal/config/meta/meta.go	95.72%	4 Missing and 1 partial ⚠️
internal/config/env_provider/unflatten.go	93.87%	2 Missing and 1 partial ⚠️
internal/config/meta/mapping.go	94.64%	2 Missing and 1 partial ⚠️
internal/config/base.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #892      +/-   ##
==========================================
+ Coverage   27.19%   29.60%   +2.41%     
==========================================
  Files         198      203       +5     
  Lines        8166     8575     +409     
==========================================
+ Hits         2221     2539     +318     
- Misses       5811     5898      +87     
- Partials      134      138       +4     

Flag	Coverage Δ
go	29.60% <74.27%> (+2.41%)	⬆️

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