fix(i18n): backfill providers.tierOverride* keys into vi.json (#7838 base-red)

#7838 added six providers.tierOverride* keys to en.json without the Vietnamese
counterparts; i18n-vi-completeness (key parity + both ICU checks) fails on the
release tip for every fresh PR run. Translated using the locale's existing tier
vocabulary and inserted at the mirrored position.

changelog.d/maintenance/7838-vi-tier-override-keys.md

@@ -0,0 +1 @@
+- **fix(i18n):** backfill the six `providers.tierOverride*` keys #7838 added to en.json into vi.json (translated with the locale's existing tier vocabulary) — their absence failed `i18n-vi-completeness` (key parity + both ICU checks) on the release tip for every fresh PR run.

src/i18n/messages/vi.json

@@ -4951,6 +4951,12 @@
     "m365TierIndividualOption": "Individual (default)",
     "m365TierEduOption": "Education",
     "m365TierEnterpriseOption": "Enterprise / Work",
+    "tierOverrideLabel": "Ghi đè tầng định tuyến",
+    "tierOverrideAuto": "Tự động (định tuyến quyết định)",
+    "tierOverrideFree": "Miễn phí",
+    "tierOverrideCheap": "Giá rẻ",
+    "tierOverridePremium": "Cao cấp",
+    "tierOverrideHelpText": "Ghim nhà cung cấp này vào một tầng định tuyến thay vì để OmniRoute suy ra từ giá mô hình.",
     "rateLimitOverridesSection": "Rate Limit Overrides",
     "rateLimitOverridesMaxConcurrentHint": "Max concurrent requests override for this connection. Overrides the account-level cap.",
     "rateLimitOverridesMaxConcurrentLabel": "Max Concurrent (Rate Limit)",