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>

CLAUDE.md

@@ -566,7 +566,7 @@ For detailed deployment instructions, see [HTTP Deployment Guide](./docs/HTTP_DE
 
 **Technical Details**:
 - `src/http-server-single-session.ts` - Single-session implementation (partial fix)
-- `src/http-server-fixed.ts` - Direct JSON-RPC implementation (complete fix)
+- `src/http-server.ts` - Direct JSON-RPC implementation (complete fix)
 - `src/utils/console-manager.ts` - Console output isolation
 - Use `USE_FIXED_HTTP=true` to enable the fixed implementation