feat(generator): support output_dir and build_extensions config for generated files

Now the code generator supports specifying a custom output directory and extension/name template for generated DI files via build.yaml ( and ). This allows placing all generated code in custom folders and using flexible naming schemes.

docs: update all user docs and tutorials to explain new output_dir/build_extensions config

- Added detailed usage and YAML examples to cherrypick_generator/README.md
- Synced full_tutorial_en.md and full_tutorial_ru.md (advanced codegen section) with explanation of new configuration and impact on imports
- Updated quick_start_en.md and quick_start_ru.md to mention advanced customization and point to tutorials
- Added troubleshooting and tips for custom output/imports in docs

doc/full_tutorial_en.md

@@ -379,6 +379,45 @@ You can use CherryPick in Dart CLI, server apps, and microservices. All major fe
 
 ---
 
+### Advanced: Customizing Generated Code Location
+
+CherryPick's code generator now supports flexible output configuration via `build.yaml`.
+
+You can control both the output directory (using `output_dir`) and filename templates (using `build_extensions`):
+
+```yaml
+targets:
+  $default:
+    builders:
+      cherrypick_generator|inject_generator:
+        options:
+          build_extensions:
+            '^lib/app.dart': ['lib/generated/app.inject.cherrypick.g.dart']
+          output_dir: lib/generated
+        generate_for:
+          - lib/**.dart
+      cherrypick_generator|module_generator:
+        options:
+          build_extensions:
+            '^lib/di/{{}}.dart': ['lib/generated/di/{{}}.module.cherrypick.g.dart']
+          output_dir: lib/generated
+        generate_for:
+          - lib/**.dart
+```
+
+- **output_dir**: Folder where all generated files will be placed.
+- **build_extensions**: Allows full customization of generated file names and subfolders.
+
+If you use these, be sure to update your imports accordingly, e.g.:
+```dart
+import 'package:your_project/generated/app.inject.cherrypick.g.dart';
+```
+If not specified, generated files will appear next to your source files, as before.
+
+---
+
+---
+
 ## Conclusion
 
 **CherryPick** is a modern DI solution for Dart and Flutter, combining a concise API and advanced annotation/codegen features. Scopes, parameterized providers, named bindings, and field-injection make it great for both small and large-scale projects.