fix: preserve externally added translation keys

[samuelstroschein]

Fixes #219

Summary

• verify watched resource fingerprints immediately before every Sherlock export
• abort stale saves and request reconciliation when an external edit is detected or already pending
• cover edits that race both before watcher delivery and during pending reconciliation
• add a patch changeset

Validation

• pnpm test (275 passed, 2 skipped, 2 todo)
• pnpm run build
• git diff --check

[chatgpt-codex-connector]

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