Add skills to the agent

[paulinea]

Inputs

Here is a file provided by Slim Namouchi:
Skill_OUDS.zip

Verbatims from Slim:

The concept: provide the AI ​​with everything it needs to generate correct OUDS code on the first try—tokens, 
API signatures, components, and templates—without hallucinating parameter names or hardcoded values.

The skill is structured across five files:
- SKILL.md: mandatory rules, checklist, and OudsTheme setup
- references/tokens.md: all tables for colors, typography, spacing, and borders
- references/components.md: full signatures for every v1.6.0 component
- references/custom-ors.md: pattern for custom components (pending the official implementation)
- references/templates.md: ready-to-use full-screen templates and lists

We deliberately split the content into multiple files rather than using a single monolithic one: 
the main SKILL.md file stays under 150 lines and serves as the entry point, while the AI ​​loads 
reference files only when needed (e.g., tokens when looking up a color, components.md when 
implementing an OudsButton). A single 500+ line file would be loaded in its entirety every time, 
unnecessarily consuming the context window and diluting the model's focus.

[pylapp]

Suggested also by @ttassain

[pylapp]

@florentmaitre Suggested PR #1436 :-D