Strictness level — controls threshold scaling.
relaxed = 2.0x (thresholds doubled, more lenient),
default = 1.0x, strict = 0.5x (thresholds halved).
Can also be a custom float like 0.7.
Builtin language profiles: default plugin settings for specific languages.
Returns (plugin_name, enabled, options) tuples. Users can override via [languages.xx.plugins.yy].