feat: enhanced authentication logging for better debugging (fixes #22, #16)

- Added specific error reasons for auth failures: no_auth_header, invalid_auth_format, invalid_token
- Fixed AUTH_TOKEN_FILE support in Docker production stacks (issue #16)
- Added AUTH_TOKEN_FILE support to single-session HTTP server for consistency
- Enhanced security by removing token lengths from logs
- Added token trimming and empty token validation
- Updated Docker entrypoint to properly support AUTH_TOKEN_FILE
- Bumped version to 2.7.10

This improves debugging for mcp-remote authentication issues and enables
proper Docker secrets usage in production environments.

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

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "n8n-mcp",
-  "version": "2.7.9",
+  "version": "2.7.10",
   "description": "Integration between n8n workflow automation and Model Context Protocol (MCP)",
   "main": "dist/index.js",
   "bin": {
@@ -41,6 +41,7 @@
     "test:tools-documentation": "node dist/scripts/test-tools-documentation.js",
     "test:mcp:update-partial": "node dist/scripts/test-mcp-n8n-update-partial.js",
     "test:update-partial:debug": "node dist/scripts/test-update-partial-debug.js",
+    "test:auth-logging": "tsx scripts/test-auth-logging.ts",
     "sanitize:templates": "node dist/scripts/sanitize-templates.js",
     "db:rebuild": "node dist/scripts/rebuild-database.js",
     "db:init": "node -e \"new (require('./dist/services/sqlite-storage-service').SQLiteStorageService)(); console.log('Database initialized')\"",