all: Run modernize -fix ./... (#4)

gen: Fix inheritance for partial-override locales

mergeStruct compared entire arrays with IsZero, so a locale that
defined only some month or day names was treated as fully present and
no slots were filled from the parent. For example, en-GB should inherit
missing values through en-001 to en. Add mergeArray to merge
element-by-element, matching the existing key-by-key behavior of
mergeMap.

Add tests covering partial array inheritance and child-value
preservation.

Regenerated golocales.autogen.go from:
https://www.unicode.org/Public//cldr/48.1/core.zip

Closes #1

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

First take