chore: bump version to 2.8.3 and update changelog

- Updated version in package.json and package.runtime.json
- Updated version badge in README.md
- Added comprehensive changelog entry for v2.8.3
- Fixed TypeScript lint errors in test files by making env vars optional
- Fixed edge-cases test to include required NODE_ENV

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

CLAUDE.md

@@ -178,6 +178,7 @@ The MCP server exposes tools in several categories:
 
 ### Agent Interaction Guidelines
 - Sub-agents are not allowed to spawn further sub-agents
+- When you use sub-agents, do not allow them to commit and push. That should be done by you
 
 # important-instruction-reminders
 Do what has been asked; nothing more, nothing less.