adds the ADR 001 document for future tasks

[eLRuLL]

Description

Adds ADR 001: Resource platform & control plane (docs/estela/adr-001-resource-platform-control-plane.md). The document records the agreed direction for upcoming refactors: control plane vs data plane, generic Resource (desired vs observed state), asynchronous reconciliation by workers, idempotency, configurable execution backends (including local development without Kubernetes), and strangler-pattern / safe cutover for production and long-running jobs.

This is documentation only; no runtime or API behavior changes.

Issue

• N/A — docs-only ADR; link an issue here if one exists.

Checklist before requesting a review

• I have performed a self-review of my code.
• My code follows the style guidelines of this project.
• I have made corresponding changes to the documentation.
• New and existing tests pass locally with my changes. (no code changes; not applicable)
• If this change is a core feature, I have added thorough tests. (not applicable)
• If this change affects or depends on the behavior of other estela repositories, I have created pull requests with the relevant changes in the affected repositories. Please, refer to our official documentation. (not applicable)
• I understand that my pull request may be closed if it becomes obvious or I did not perform all of the steps above.

[github-actions]

Docs preview

New docs deployment: [7b3ec59bb61aab7f48596e40dc2d5db8e7d8b62c]!
Check out the docs preview here 👈

[joaquingx]

Nice 👍 , please read this @erick-GeGe