refactor(generator): migrate cherrypick_generator to analyzer element2 API

- Fully migrated core cherrypick_generator and submodules to new analyzer element2 system:
  - Updated all GeneratorForAnnotation overrides to use Element2, ClassElement2, MethodElement2, FieldElement2 and new annotation/metadata access patterns.
  - Migrated signature and bodies for helpers, parsers, annotation validators, meta utils, and type parsers.
  - Fixed tests to use readerWriter instead of deprecated reader argument.
  - Refactored usage of now-absent 'metadata', 'parameters', 'fields', 'methods', 'source', and similar members to use correct *.firstFragment.* or API alternatives.
  - Cleaned up old imports and unused code.

test(generator): update generator integration tests

- Updated test calls to use correct TestReaderWriter type and bring test infra in line with current build_runner/testing API.

build: update dependencies and pubspec to support latest analyzer/build ecosystem

- Raised Dart SDK and package constraints as required for generated code and codegen plugins.
- Updated pubspecs in root/examples as needed by build warnings.

docs: add plots and assets (new files)

BREAKING CHANGE:
- Requires Dart 3.8+ and analyzer that supports element2.
- All downstream codegen/tests depending on Element API must migrate to Element2 signatures and data model.

examples/postly/pubspec.yaml

@@ -5,21 +5,20 @@ publish_to: 'none'
 version: 1.0.0+1
 
 environment:
-  sdk: ">=3.6.0 <4.0.0"
+  sdk: ">=3.8.0 <4.0.0"
 
 
 dependencies:
   flutter:
     sdk: flutter
 
-  cherrypick:
-    path: ../../cherrypick
-  cherrypick_annotations:
-    path: ../../cherrypick_annotations
+  cherrypick: any
+  cherrypick_annotations: any
   
   dio: ^5.4.0
   retrofit: ^4.0.3
-  freezed_annotation: ^2.4.4
+  freezed_annotation: ^3.0.0
+  json_annotation: ^4.9.0
   dartz: ^0.10.1
   flutter_bloc: ^9.1.1
   auto_route: ^10.1.0+1
@@ -28,25 +27,23 @@ dependencies:
   cupertino_icons: ^1.0.8
 
   talker_flutter: ^5.0.0
-  talker_cherrypick_logger:
-    path: ../../talker_cherrypick_logger
+  talker_cherrypick_logger: any
   talker_dio_logger: ^5.0.0
   talker_bloc_logger: ^5.0.0
-
+  
 dev_dependencies:
   flutter_test:
     sdk: flutter
 
-  flutter_lints: ^5.0.0
+  flutter_lints: ^6.0.0
 
-  build_runner: 2.4.15
-  cherrypick_generator:
-    path: ../../cherrypick_generator
+  build_runner: ^2.5.0
+  cherrypick_generator: any
   
   json_serializable: ^6.9.0
-  retrofit_generator: ^9.1.5
+  retrofit_generator: ^10.0.5
   auto_route_generator: ^10.0.1
-  freezed: ^2.5.8
+  freezed: ^3.0.0
   melos: ^6.3.2
 
 flutter: