fix: refactor annotation retrieval

[techouse]

Why

The test suite started failing when dependency resolution selected analyzer 14.4.0 (see CI run 34732754518). The EnviedGenerator was still invoked, but generateForAnnotatedElement then re-scanned element.metadata.annotations and identified Envied annotations with:

annotation.element?.displayName == 'Envied'

With Analyzer 14.4.0, that secondary lookup no longer matched the @Envied annotations. The resulting annotation list was empty, so generation produced only the standard header with an empty generated_from: value. This caused generated output, workspace asset tracking, and hidden-env-file tests to fail. The same code passed with Analyzer 14.3.0; the previous successful run (32518422640) resolved Analyzer 14.1.0.

Change

Collect annotations through source_gen's type checker instead:

final List<ConstantReader> enviedAnnotations = _typeChecker(
  Envied,
  inPackage: 'envied',
).annotationsOf(element).map(ConstantReader.new).toList(growable: false);

This matches annotations by their resolved type and package rather than depending on Analyzer's annotation element display name. It also preserves support for multiple @Envied annotations.

This fixes the compatibility issue without narrowing the existing dependency constraint (analyzer: ">=8.0.0 <15.0.0"). No build_runner, build_test, or Melos changes are required.

Verification

• Analyzer 14.4.0 resolves successfully.
• melos test passes for both packages.
• melos run validate passes.
• Existing tests covering multiple annotations and hidden environment files pass.

[techouse]

@petercinibulk Please throw an eye on this, once you get a minute 🙏 It's a blocker for 1.3.9.