Branches handleRefreshToken to call the dedicated Cursor refresh
route instead of the generic /refresh route, which silently 502s
for Cursor connections today since they carry no refresh token.
Every other provider's refresh behavior is unaffected. Adds the
cursorSessionUnchanged i18n key and syncs it (plus a pre-existing,
unrelated 28-key backlog) across all 42 locale files.
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