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>

Dockerfile

@@ -45,8 +45,9 @@ COPY data/nodes.db ./data/
 COPY src/database/schema-optimized.sql ./src/database/
 COPY .env.example ./
 
-# Copy entrypoint script
+# Copy entrypoint script and config parser
 COPY docker/docker-entrypoint.sh /usr/local/bin/
+COPY docker/parse-config.js /app/docker/
 RUN chmod +x /usr/local/bin/docker-entrypoint.sh
 
 # Add container labels