TS: Fix profile apply/create, fix slice match arrays, rewrite example tests

[ryukzak]

Profile class fixes

• apply() now sets fixed-value fields and auto-populates discriminator-only slice stubs, matching create() behavior
• apply() no longer redundantly assigns resourceType
• Only auto-populate slices where the discriminator stub is the complete content (e.g. category VSCat). Skip type discriminators (Bundle entry) and slices with required fields beyond match keys
• Fixed-value fields get a getter but no setter
• create() split into createResource + apply for readability
• Extension apply() sets URL, uses upsert for single extensions

Slice match array fixes

• @atomic-ehr/fhirschema 0.0.9 → 0.0.10 (fix: Wrap slice match values in arrays for array elements fhirschema#15) — fixes buildMatchForSlice wrapping
• computeMatchFromSchema in codegen now also wraps sliced elements in arrays (fixes R4 BP component.code.coding from plain object to Coding[])

Example test rewrite

• Restructure all profile test files with demo-first pattern:
  • Demo tests on top — create (with validation flow), apply, from/read
  • Regression tests below — concise, focused on edge cases
• Remove all as any / as never / as unknown casts
• Add resource snapshots for fully populated profiles (bodyweight, BP, US Core Patient)
• Add example test structure guidelines to CLAUDE.md

Before/After

apply() — now auto-populates fixed fields and discriminator-only slices:

// Before
static apply (resource: Observation) {
    ensureProfile(resource, canonicalUrl);
    Object.assign(resource, { resourceType: "Observation" })
    return new Profile(resource);
}

// After
static apply (resource: Observation) {
    ensureProfile(resource, canonicalUrl);
    Object.assign(resource, {
        code: {"coding":[{"code":"29463-7","system":"http://loinc.org"}]},
    })
    resource.category = ensureSliceDefaults(
        [...(resource.category ?? [])],
        Profile.VSCatSliceMatch,
    );
    return new Profile(resource);
}

Slice auto-population — only for discriminator-complete slices:

// category VSCat: auto-populated (discriminator IS the content)
resource.category = ensureSliceDefaults([...], VSCatSliceMatch);

// Bundle entry: NOT auto-populated (user must provide the Patient resource)
// BP component: auto-populated (valueQuantity is must-support, not required)

Slice match data — coding now correctly wrapped as array everywhere:

// Before (both fhirschema and computeMatchFromSchema paths)
{"coding":{"code":"vital-signs","system":"..."}}
{"code":{"coding":{"code":"8480-6","system":"http://loinc.org"}}}

// After
{"coding":[{"code":"vital-signs","system":"..."}]}
{"code":{"coding":[{"code":"8480-6","system":"http://loinc.org"}]}}