fix(i18n): require an explicit locale on presentation helpers

[orangeCatDeveloper]

Summary

Presentation helpers across desktop renderer, @maka/core, and @maka/ui defaulted their locale parameter to 'zh', so a caller that forgot to pass it rendered Chinese to English users with no type error. This PR removes every such default (24 helpers, 23 files) so the locale is a required argument. No production caller relied on a default — every one already passed the locale it had in scope — so the runtime behavior is unchanged; only the type-level guarantee is new. Tests that leaned on the default now pass 'zh' explicitly, and each touched helper gained one 'en' assertion so the English path is proven rather than assumed.

The six @maka/ui streaming helpers with the same defect are fixed in #4524 and are not touched here; the two OAuth result helpers are fixed in #4551.

Refs #2672

Verification

workspace typecheck:                    0 errors
packages/core tests:                    774 pass / 0 fail
packages/ui tests:                      334 pass / 0 fail
desktop main tests (dist):              1995 pass / 0 fail
renderer architecture check:            passed against origin/main
biome (changed files):                  clean
git grep "locale: UiLocale = 'zh'|locale ?? 'zh'" (non-test): only the #4524 / #4551 sites remain

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Tool(s) and scope: Claude Code — implementation, tests, and this description, under the contributor's direction; the commit carries a Generated-by: Claude Code trailer.

Checklist

• Tests cover the change and fail without it