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>

docker/README.md

@@ -0,0 +1,87 @@
+# Docker Usage Guide for n8n-mcp
+
+## Running in HTTP Mode
+
+The n8n-mcp Docker container can be run in HTTP mode using several methods:
+
+### Method 1: Using Environment Variables (Recommended)
+
+```bash
+docker run -d -p 3000:3000 \
+  --name n8n-mcp-server \
+  -e MCP_MODE=http \
+  -e AUTH_TOKEN=your-secure-token-here \
+  ghcr.io/czlonkowski/n8n-mcp:latest
+```
+
+### Method 2: Using docker-compose
+
+```bash
+# Create a .env file
+cat > .env << EOF
+MCP_MODE=http
+AUTH_TOKEN=your-secure-token-here
+PORT=3000
+EOF
+
+# Run with docker-compose
+docker-compose up -d
+```
+
+### Method 3: Using a Configuration File
+
+Create a `config.json` file:
+```json
+{
+  "MCP_MODE": "http",
+  "AUTH_TOKEN": "your-secure-token-here",
+  "PORT": "3000",
+  "LOG_LEVEL": "info"
+}
+```
+
+Run with the config file:
+```bash
+docker run -d -p 3000:3000 \
+  --name n8n-mcp-server \
+  -v $(pwd)/config.json:/app/config.json:ro \
+  ghcr.io/czlonkowski/n8n-mcp:latest
+```
+
+### Method 4: Using the n8n-mcp serve Command
+
+```bash
+docker run -d -p 3000:3000 \
+  --name n8n-mcp-server \
+  -e AUTH_TOKEN=your-secure-token-here \
+  ghcr.io/czlonkowski/n8n-mcp:latest \
+  n8n-mcp serve
+```
+
+## Important Notes
+
+1. **AUTH_TOKEN is required** for HTTP mode. Generate a secure token:
+   ```bash
+   openssl rand -base64 32
+   ```
+
+2. **Environment variables take precedence** over config file values
+
+3. **Default mode is stdio** if MCP_MODE is not specified
+
+4. **Health check endpoint** is available at `http://localhost:3000/health`
+
+## Troubleshooting
+
+### Container exits immediately
+- Check logs: `docker logs n8n-mcp-server`
+- Ensure AUTH_TOKEN is set for HTTP mode
+
+### "n8n-mcp: not found" error
+- This has been fixed in the latest version
+- Use the full command: `node /app/dist/mcp/index.js` as a workaround
+
+### Config file not working
+- Ensure the file is valid JSON
+- Mount as read-only: `-v $(pwd)/config.json:/app/config.json:ro`
+- Check that the config parser is present: `docker exec n8n-mcp-server ls -la /app/docker/`