fix: prevent false positives in translation linting results

Ensures each translation area independently tracks its missing files,
preventing files from being incorrectly reported as missing in multiple areas.
This resolves an issue where PRIVACY.md was incorrectly shown as missing
in the WEBVIEW area when it should only appear in the DOCS area.

Signed-off-by: Eric Wheeler <[email protected]>

Author: Eric Wheeler

locales/__tests__/lint-translations.test.ts

@@ -264,12 +264,12 @@ function formatResults(results: Results, checkTypes: string[], options: LintOpti
 
 	// Group errors by type for summary
 	const errorsByType = new Map<string, string[]>()
-	const missingByFile = new Map<string, Set<string>>()
 
 	for (const [area, areaResults] of Object.entries(results)) {
 		let areaHasIssues = false
 		const extraByLocale = new Map<string, Map<string, TranslationIssue[]>>()
 		let missingCount = 0
+		const missingByFile = new Map<string, Set<string>>()
 
 		for (const [locale, localeResults] of Object.entries(areaResults)) {
 			let localeMissingCount = 0