fix: add Docker configuration file support (fixes #105)

This commit adds comprehensive support for JSON configuration files in Docker containers,
addressing the issue where the Docker image fails to start in server mode and ignores
configuration files.

## Changes

### Docker Configuration Support
- Added parse-config.js to safely parse JSON configs and export as shell variables
- Implemented secure shell quoting to prevent command injection
- Added dangerous environment variable blocking for security
- Support for all JSON data types with proper edge case handling

### Docker Server Mode Fix
- Added support for "n8n-mcp serve" command in entrypoint
- Properly transforms serve command to HTTP mode
- Fixed missing n8n-mcp binary issue in Docker image

### Security Enhancements
- POSIX-compliant shell quoting without eval
- Blocked dangerous variables (PATH, LD_PRELOAD, etc.)
- Sanitized configuration keys to prevent invalid shell variables
- Protection against shell metacharacters in values

### Testing
- Added 53 comprehensive tests for Docker configuration
- Unit tests for parsing, security, and edge cases
- Integration tests for Docker entrypoint behavior
- Security-focused tests for injection prevention

### Documentation
- Updated Docker README with config file mounting examples
- Enhanced troubleshooting guide with config file issues
- Added version bump to 2.8.2

### Additional Files
- Included deployment-engineer and technical-researcher agent files

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

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

README.md

@@ -2,7 +2,7 @@
 
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![GitHub stars](https://img.shields.io/github/stars/czlonkowski/n8n-mcp?style=social)](https://github.com/czlonkowski/n8n-mcp)
-[![Version](https://img.shields.io/badge/version-2.8.1-blue.svg)](https://github.com/czlonkowski/n8n-mcp)
+[![Version](https://img.shields.io/badge/version-2.8.2-blue.svg)](https://github.com/czlonkowski/n8n-mcp)
 [![npm version](https://img.shields.io/npm/v/n8n-mcp.svg)](https://www.npmjs.com/package/n8n-mcp)
 [![codecov](https://codecov.io/gh/czlonkowski/n8n-mcp/graph/badge.svg?token=YOUR_TOKEN)](https://codecov.io/gh/czlonkowski/n8n-mcp)
 [![Tests](https://img.shields.io/badge/tests-1356%20passing-brightgreen.svg)](https://github.com/czlonkowski/n8n-mcp/actions)