fix(docx-io): strip local comment tracking tokens

[loc01227175513]

Summary

• strip DOCX comment tracking tokens from local comment fallback document content
• strip tokens recursively from local rich comment bodies during re-import
• add regression tests for plain text and rich comment body re-import paths

Verification

• npm exec --yes bun -- test packages/docx-io/src/lib/applyDocxTracking.spec.ts packages/docx-io/src/lib/parseDocxTracking.spec.ts
• yarn biome check packages/docx-io/src/lib/importComments.ts packages/docx-io/src/lib/applyDocxTracking.spec.ts
• yarn turbo build --filter=./packages/docx-io

Notes:

• yarn turbo typecheck --filter=./packages/docx-io still hits the same TypeScript internal Debug Failure on the unmodified PR head baseline under Node v22.15.0.
• yarn workspace @platejs/docx-io lint still reports many pre-existing package diagnostics outside the touched files.