feat: Allow custom type declaration in SimpleSchema

[BigGold1310]

Description of your changes

Allows the definition of custom types within a SimpleSchema declaration.
Looks like:

apiVersion: aws.u5d.io/v1
kind: XEKS
metadata:
  name: test
spec:
  request: myType
status:
  result: myType
customTypes:
  myType:
    value1: string | required=true
    value2: integer | default=42

Fixes #199

I have:

• Read and followed Crossplane's contribution process.
• Run ./nix.sh flake check to ensure this PR is ready for review.
• Added or updated unit tests.
• Linked a PR or a docs tracking issue to document this change.
• Added backport release-x.y labels to auto-backport this PR.

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[coderabbitai]

📝 Walkthrough

Walkthrough

The XRD generator now reads customTypes from SimpleSchema input and passes them to spec and status OpenAPI conversion. A table-driven test validates reusable nested objects, required fields, integer defaults, and generated XRD metadata.

Changes

SimpleSchema custom type support

Layer / File(s)	Summary
Custom type schema generation cmd/crossplane/xrd/generate.go, cmd/crossplane/xrd/generate_test.go	inputXR captures customTypes. SimpleSchema conversion uses the custom types for both spec and status. Tests validate nested request and result objects, required fields, integer typing, default value 42, and namespaced XRD metadata.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: adamwg

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Important

Pre-merge checks failed

Please resolve all errors before merging. Addressing warnings is optional.

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Feature Gate Requirement	❓ Inconclusive	The feature-gate check may apply to this behavior change, but the repository’s feature-flag mechanism and experimental-feature criteria are not yet verified.	Inspect existing feature gates and command behavior to determine whether this CLI enhancement requires a flag.

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The implementation reads customTypes and passes them to both spec and status schema generation, with tests for reusable nested types.
Out of Scope Changes check	✅ Passed	The code and test changes directly support custom type handling in SimpleSchema and contain no unrelated changes.
Breaking Changes	✅ Passed	The change only adds optional customTypes handling in cmd/crossplane/xrd; it removes no public fields or flags and preserves existing SimpleSchema behavior.
Title check	✅ Passed	The title is 51 characters, stays under 72 characters, and clearly describes support for custom types in SimpleSchema.
Description check	✅ Passed	The description explains the customTypes feature, provides an example, references issue #199, and notes test coverage.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@cmd/crossplane/xrd/generate_test.go`:
- Around line 784-803: Update the comparison in the test around the generated
schema to include JSONSchemaProps.Required instead of globally ignoring it.
Ensure the assertions explicitly verify that both spec.request.Required and
status.result.Required contain value1, while preserving the existing comparisons
for other schema fields.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: f39acff3-182f-4bfb-b03f-6a7628e4408c

📥 Commits

Reviewing files that changed from the base of the PR and between a3f848e and 410f1d8.

📒 Files selected for processing (2)

• cmd/crossplane/xrd/generate.go
• cmd/crossplane/xrd/generate_test.go

[haarchri]

LGTM