feat: add project export and import functionality

- Implemented `pcli project export` command to export project hierarchy as JSON.
- Added `pcli project import` command to import project data from JSON.
- Created user client to fetch user details for comment attribution.
- Introduced new data structures for export and import processes.
- Ensured name-based references in exports and handled conflicts during imports.
- Added versioning and progress reporting for import operations.
- Updated documentation and specifications for new features.

.windsurf/workflows/opsx-archive.md

@@ -59,7 +59,7 @@ Archive a completed change in the experimental workflow.
    - If changes needed: "Sync now (recommended)", "Archive without syncing"
    - If already synced: "Archive now", "Sync anyway", "Cancel"
 
-   If user chooses sync, execute `/opsx:sync` logic. Proceed to archive regardless of choice.
+   If user chooses sync, use Task tool (subagent_type: "general-purpose", prompt: "Use Skill tool to invoke openspec-sync-specs for change '<name>'. Delta spec analysis: <include the analyzed delta spec summary>"). Proceed to archive regardless of choice.
 
 5. **Perform the archive**
 
@@ -153,5 +153,5 @@ Target archive directory already exists.
 - Don't block archive on warnings - just inform and confirm
 - Preserve .openspec.yaml when moving to archive (it moves with the directory)
 - Show clear summary of what happened
-- If sync is requested, use /opsx:sync approach (agent-driven)
+- If sync is requested, use the Skill tool to invoke `openspec-sync-specs` (agent-driven)
 - If delta specs exist, always run the sync assessment and show the combined summary before prompting