+prefixed custom config keys with dict values mangled in dbt_project.yml top-level

[ntantri]

Bug

dbt-autofix mangles +-prefixed custom config keys that have dict values when they appear at the top level of models: (or other node-type sections) in dbt_project.yml.

The root cause: changeset_dbt_project_prefix_plus_for_config doesn't check for + prefix in its else branch, it assumes any unrecognised key with a dict value is a project path and recurses into it. rec_check_yaml_path already handles this correctly at nested levels.

Reproduction

# input
models:
  +endpoint_settings: &defaults
    owner: my-team
    lifecycle: production
    retentionCategory:
      category: internal
      subCategory: internal.benchmarking

# actual output — broken
models:
  +endpoint_settings: &defaults
    retentionCategory:
      +category: "internal"          # wrong: +prefix on plain data
      +meta:
        subCategory: internal.benchmarking
    +meta:
      owner: my-team
      lifecycle: production

# expected output
models:
  +meta:
    endpoint_settings: &defaults
      owner: my-team
      lifecycle: production
      retentionCategory:
        category: internal
        subCategory: internal.benchmarking

category happens to be a valid dbt config field, so it gets + prefixed. Everything else gets shoved under +meta inside the anchor. This breaks YAML anchor inheritance for any project using <<: *defaults overrides.

Fix

Add elif k.startswith("+") before the else branch in changeset_dbt_project_prefix_plus_for_config, move the key to +meta as a unit instead of recursing. This matches what rec_check_yaml_path already does for nested keys.

Tested on 0.20.2 and 0.20.4.

I can raise a PR incoming.