PR #2367 introduced CLIOverrides to give --state-values-set element-by-element
array merge semantics. However, nested helmfile values (helmfiles[].values:)
were also routed into CLIOverrides, causing their arrays to merge instead of
replace. This broke the pre-v1.3.0 behavior where passing an array via
helmfiles[].values: would fully replace the child's default array.
Add OverrideValuesAreCLI flag to SubhelmfileEnvironmentSpec so the loader can
distinguish CLI flags from nested helmfile values. CLI values continue using
CLIOverrides (element-by-element merge); nested helmfile values now use Values
(Sparse merge strategy → full array replacement).
Fixes#2451
Signed-off-by: Aditya Menon <amenon@canarytechnologies.com>
