Formatted output, possibleTypes, type name escaping, document validation

[ifmelate]

Changes for 2.2.0.

Added

• Generated files are formatted with dart_style for the language version of the package being built (from BuildStep.packageConfig), so dart format --set-exit-if-changed passes in user projects
• types.dart exports possibleTypes (Map<String, Set<String>>) for GraphQLCache(possibleTypes: ...)
• Operations are validated against the schema: unknown fields at any depth (BLD103, was root only), unknown or missing required arguments (BLD105), variable problems (BLD106), selection set and fragment type problems (BLD107). All problems are reported at once with path and line. validate_documents: false turns it off

Fixed

• Schema types named like identifiers the generated code uses (Map, String, Object, Future, Set, JsonKey, object types Decimal/Long/Byte, ...) produced code that didn't compile. They now get a trailing underscore in Dart (type Map → class Map_); __typename dispatch and possibleTypes keep the GraphQL names
• With strict_nullability, [CustomScalar!]! / [DateTime!]! / [Decimal!]! fields didn't compile because the list helpers returned nullable lists (found while adding the collision test)

Behavior change

• A build now fails for operations the schema rejects. Documented in the CHANGELOG with the escape hatch

Dependencies

• Minimum SDK raised to Dart 3.4 (Flutter 3.22): dart_style >=2.3.7 depends on analyzer 6.5+, which needs macros (SDK 3.4). Projects on older SDKs keep resolving 2.1.0. Verified locally on Dart 3.4.0 with the oldest resolvable versions (dart_style 2.3.7, build 2.4.1, build_test 2.2.2): all 144 tests pass. CI matrix moved from 3.2.0 to 3.4.0
• build: ^2.4.0 (for packageConfig), dart_style: ">=2.3.7 <4.0.0" (first version with languageVersion; works with old and new build_runner), pub_semver

Tests

• 144 tests (was 116). The compile test has a new collide variant: a schema full of colliding names, compiled, analyzed and run. The smoke client now uses GraphQLCache(possibleTypes: possibleTypes)