feat(api): implement pull request assignees and check runs endpoints

- Add PR assignees API with list, assign, and unassign operations
- Add PR check runs API with create, update, list, and delete operations
- Implement workspace finding by ID method in core service
- Update .gitignore to include .env* files while preserving .env.example
- Reorder imports in multiple API files for consistency
- Format function calls with proper line breaks across PR-related APIs
- Add wiki revision comparison endpoint with proper schema definitions
- Integrate new API modules into main application setup
- Add health check, readiness probe, and OpenAPI endpoints to main server
- Configure session management and dependency injection in main application

.gitignore

@@ -2,5 +2,7 @@
 .idea
 .codegraph
 .claude
+.env*
+!.env.example
 AGENT.md
 CLAUDE.md