Add Designish directory structure standards and definitions

[benson-08]

Hi everyone,

This PR proposes a new directory structure standard called Designish.

The idea is simple: instead of naming folders after file types, you name them
after the phase of the project lifecycle they belong to , concept, design,
make, validation, release. This makes it much easier for designers, makers, and
non-technical contributors to find their way around a project without needing a
software background.

It also adds a 40_stewardship/ section for maintenance, repair, and recovery,
bringing circular economy thinking into the structure from the start.

Why I'm working on this?

I'm currently contributing to CK-01,
a community stroller project in Zeitz (Germany) rooted in the ZEKIWA legacy —
once the largest pram factory in Europe. CK-01 is a real-world open hardware
project exploring how a circular product can be developed openly and
participatively, involving parents, engineers, craftspeople, and researchers.

Working on that project made the gap very visible: existing OSH directory
standards are structured for developers, not for the cross-disciplinary,
designer-led teams that circular hardware projects actually need. Designish
is a direct response to that experience.

What's new?

• mod/designish/ — definition and full documentation
• designish-structure.md — narrative overview and design rationale
• README.md — updated to include Designish alongside Unixish and Prusaish

Happy to discuss naming, structure choices, or anything else. Thanks for taking
a look!