Update agent skills

[roger-datocms]

1. Accommodate https://www.datocms.com/product-updates/non-localized-focal-points and the two shapes (pre and post migration)
2. More explicit field create/update handling (validators and appearance settings)
3. Validated & clarified record localization behaviors (against docs and the api repo)

Validated against:

• Attempted use of the skill to scaffold a new, complex project from scratch (to be used later in some tests for the AI Translations plugin). The agent eventually succeeded, but only with effort. The transcript was fed back into skills-creator for the initial improvements.
• The improvements were then validated against our official docs, and cited as appropriate
• Then triply-verified against API source code to make sure skills + docs + API all align now