Add a basic Dockerfile

[PeterDaveHello]

Add a Dockerfile to simplify distribution and deployment of htmlq.

Providing an official Dockerfile makes it significantly easier for users to quickly run htmlq in a consistent, isolated environment without manual setup. It also facilitates seamless integration into automated workflows and CI/CD pipelines.

Key benefits:

• Ensures consistent builds and reproducible environments.
• Simplifies deployment and usage across diverse systems.
• Enables straightforward integration with container-based CI/CD tools.