Named configuration profiles

[MatthewMckee4]

Support named profiles in karva.toml that bundle different settings for different contexts:

[profile.default]
fail-fast = false
retry = 0

[profile.ci]
fail-fast = true
retry = 2
timeout = "120s"

[profile.coverage]
num-workers = 1
show-output = true

Select with --profile:

karva test --profile ci

Profiles inherit from default and override specific settings. This avoids needing separate config files or long CLI flags for different environments.

See: https://nexte.st/docs/configuration/nextest-toml/#profiles