Preserve relative VS Code workspace paths

[0x7ffc]

Summary

• preserve relative repository paths from workspace.yaml in generated .code-workspace folders
• keep absolute path resolution only for dedupe and reconciliation
• add unit and sync-level regression coverage for the relative-path output

Test Plan

• bun test tests/unit/core/vscode-workspace.test.ts tests/unit/cli/workspace-setup.test.ts tests/e2e/vscode-workspace-setup.test.ts
• node dist/index.js workspace sync (smoke-tested against WiseTechGlobal/ilcore-sdd)