i18n Messages

Scope:

• packages/*/src/messages/i18n.ts + code consuming those messages via nls.localize
• NOT package.json/package.nls.json nls strings (command titles etc.)
• NOT unrelated code

Placeholder semantics

nls.localize(key, ...args) substitutes via node:util.format — packages/salesforcedx-vscode-i18n/src/i18n/message.ts:50 (return format(possibleLabel, ...labelArgs)).