refactor: use Exchange Node for Office conversion

[OTime-Coder]

Summary

• replace @univer-cli/unit-exchange and the uexcli runtime with @univerjs-pro/exchange-node and its native binding
• keep a thin application adapter for legacy suffixes, formula defaults, CSV/TSV selectors, and stable CLI error codes
• update native dependency packaging audits and architecture documentation
• add native round-trip coverage for Sheet, Base, Doc, and Slide units

Validation

• pnpm check
• 18 CLI test files and 91 CLI tests passed
• production release tgz built with release:cli --channel=dev --prepare-only
• release tgz installed globally in an isolated prefix; version, Skills, doctor, daemon, Gateway, and Viewer checks passed
• installed tgz imported a real XLSX and exported it back to a structurally valid XLSX through Exchange Node
• npm publish --dry-run passed