TS: validate() should check required fields inside slice elements

[ryukzak]

The generated validate() method checks slice cardinality (e.g. systolic and diastolic slices exist) but does not validate required fields within slice elements.

Example

The BP profile requires component.valueQuantity (min: 1) for both systolic and diastolic slices. After create(), auto-populated stubs have only the discriminator code but no valueQuantity:

const profile = bpProfile.create({
    status: "final",
    subject: { reference: "Patient/pt-1" },
});

// Only reports missing effective[x], but should also report
// missing valueQuantity in systolic and diastolic component stubs
profile.validate().errors
// Actual:   ["at least one of effectiveDateTime, effectivePeriod is required"]
// Expected: should also include errors about missing component.valueQuantity

Scope

• Affects src/api/writer-generator/typescript/profile-validation.ts
• Needs to iterate slice elements and check required fields within each matched slice
• Applies to all profiles with required fields inside slices (BP components, etc.)