Configurable lint rules via .winn-lint.json

[gregwinn]

Summary

Allow users to configure lint rules via a .winn-lint.json file in the project root. Each rule can be set to false (disabled), "warning" (informational), or "error" (fails CI with exit code 1).

Config Format

{
  "rules": {
    "single_pipe": false,
    "unused_variable": "warning",
    "empty_function_body": "error"
  }
}

• Only rules that differ from defaults need to be listed
• Without a config file, all rules default to "warning" (current behavior)
• Unknown rule names produce a warning on stderr
• Invalid values fall back to default with a warning

Behavior

Scenario	Exit code
No violations	0
Only warnings	0
Any errors	1

This changes the current behavior where all warnings cause exit code 1. With config, "warning" rules become informational only — only "error" rules fail CI.

New: winn lint --init

Generates a default .winn-lint.json with all 10 rules set to "warning" as a starting point.

Implementation

1. Config loading in winn_lint.erl — load_config/0 reads .winn-lint.json, parses with jsone, merges over defaults
2. Thread config through checks — check_string/2, check_file/2 accept config; each rule checks its config before emitting
3. CLI changes — run_lint loads config once, separates error vs warning counts, exits 1 only on errors
4. --init subcommand — generates default config file
5. Tests — config loading, rule suppression, severity-based exit codes
6. Docs — update cli.md, getting-started.md, CHANGELOG.md

Files to Modify

• apps/winn/src/winn_lint.erl
• apps/winn/src/winn_cli.erl
• apps/winn/test/winn_lint_tests.erl
• docs/cli.md
• docs/getting-started.md
• CHANGELOG.md

Part of v0.9.0 — Developer Tooling