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>

scripts/test-docker-config.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+
+# Script to run Docker config tests
+# Usage: ./scripts/test-docker-config.sh [unit|integration|all]
+
+set -e
+
+MODE=${1:-all}
+
+echo "Running Docker config tests in mode: $MODE"
+
+case $MODE in
+  unit)
+    echo "Running unit tests..."
+    npm test -- tests/unit/docker/
+    ;;
+  integration)
+    echo "Running integration tests (requires Docker)..."
+    RUN_DOCKER_TESTS=true npm run test:integration -- tests/integration/docker/
+    ;;
+  all)
+    echo "Running all Docker config tests..."
+    npm test -- tests/unit/docker/
+    if command -v docker &> /dev/null; then
+      echo "Docker found, running integration tests..."
+      RUN_DOCKER_TESTS=true npm run test:integration -- tests/integration/docker/
+    else
+      echo "Docker not found, skipping integration tests"
+    fi
+    ;;
+  coverage)
+    echo "Running Docker config tests with coverage..."
+    npm run test:coverage -- tests/unit/docker/
+    ;;
+  security)
+    echo "Running security-focused tests..."
+    npm test -- tests/unit/docker/config-security.test.ts tests/unit/docker/parse-config.test.ts
+    ;;
+  *)
+    echo "Usage: $0 [unit|integration|all|coverage|security]"
+    exit 1
+    ;;
+esac
+
+echo "Docker config tests completed!"