fix(core): preserve JSON Schema enum case order

[schani]

Bug

C++ (and, as it turns out, every other language) emitted enum cases in
alphabetical order instead of the order they appear in the source JSON
Schema / JSON enum array.

Repro from the issue:

quicktype -l c++ --code-format with-getter-setter --wstring use-string --const-style west-const --type-style pascal-case --member-style camel-case --enumerator-style pascal-case --no-boost -s schema test.json

with schema property "enum": ["B", "A", "E"] produced:

enum class ErrorCode : int { A, B, E };

instead of preserving the declared order B, A, E.

Root cause

ConvenienceRenderer.forEachEnumCase (in
packages/quicktype-core/src/ConvenienceRenderer.ts) unconditionally
sorted enum case names alphabetically by their rendered Name before
handing them to a language renderer's emitEnum:

const sortedCaseNames = mapSortBy(caseNames, (n) =>
    defined(this.names.get(n)),
);
this.forEachWithBlankLines(sortedCaseNames, blankLocations, f);

forEachEnumCase is called by essentially every language's emitEnum
(C++, C#, Java, Kotlin, Swift, Python, Go, Rust, PHP, Ruby, etc.), so
this alphabetization was not C++-specific — it affected all generators.
The underlying caseNames map already reflects the original
schema/JSON input order (JS Map/Set preserve insertion order), so
the fix is simply to stop forcibly re-sorting it, mirroring how
forEachClassProperty already preserves declared property order by
default (only alphabetizing when the existing, opt-in
_alphabetizeProperties renderer option is set).

Fix

Removed the unconditional mapSortBy alphabetization in
forEachEnumCase, so enum cases are emitted in the same order they
appear in the source input.

Test coverage

• Added test/unit/enum-order.test.ts, which reproduces the issue's
  exact schema (enum: ["B", "A", "E"]) and asserts the generated C++
  contains enum class ErrorCode : int { B, A, E };. This fails on
  unfixed code (previously emitted A, B, E) and passes after the fix.
• End-to-end fixture coverage already exists via
  test/inputs/schema/enum.schema, whose enum arrays
  (["lawful", "neutral", "chaotic"], ["good", "neutral", "evil"])
  are non-alphabetical and are exercised for C++ through the
  schema-cplusplus fixture (not in that language's skipSchema list),
  giving ongoing round-trip regression coverage for this case.

Verification

• npm run build passes.
• npx vitest run test/unit — all 171 unit tests pass, including the
  new regression test.
• QUICKTEST=true FIXTURE=schema-cplusplus script/test — all 70 tests
  pass locally (g++ toolchain available in this environment).
• Manually re-ran the exact CLI repro from the issue; output now shows
  enum class ErrorCode : int { B, A, E };, matching input order.
• CI will additionally validate the other language fixtures that call
  forEachEnumCase.

Fixes #1289.

🤖 Generated with Claude Code