Upgrade versions, implement software product lines variation for features, storage service, and state management

[MHibriziF]

Flutter Clean Architecture with SPLE implementation

Summary

This PR builds on top of https://github.com/ristekoss/flutter-clean-architecture, the original organization boilerplate. It incorporates work from an unmerged upstream PR (#2)

Changes are layered in three stages:

Stage 1 — Inherited from upstream unmerged PR (#2 via https://github.com/yudha-haris/flutter-clean-architecture/tree/main)

• Gradle upgraded to 8.3 with full Android build config modernization
• Dependencies updated to support Flutter 3.27
• Migrated DI from manual get_it registration modules to injectable + build_runner annotation-based auto-wiring
• Bloc structure refactored to follow official flutter_bloc documentation patterns
• Removed per-feature di/ module files (product_module.dart, profile_module.dart, etc.) — replaced by @Injectable/@LazySingleton annotations

Stage 2 — Version upgrade

• Flutter upgraded to 3.41.3 / Dart 3.11.1
• Dependencies bumped accordingly

Stage 3 — Software Product Line (SPL) layer

• Added spl.yaml as single source of truth for product configuration
• Storage variability (XOR) — AppStorage abstract interface with swappable backends: flutter_secure_storage, hive, sqflite, shared_preferences. Only the active provider's impl file is generated; switching via
  CLI deletes the old and generates the new
• State management variability (OR) — global default + per-feature override supporting bloc, cubit, and riverpod. Features can mix solutions freely
• SecureStorage service removed — redundant wrapper; SecureDatabase now uses FlutterSecureStorage const directly. Auth tokens always go to the OS keychain (not a variability point)
• Feature lifecycle management — add, disable (moves to features_catalog/, preserves code), enable (restores from catalog), remove (hard delete)
• codegen/spl_manager.dart — CLI tool driving all of the above, with Mason integration (falls back to inline templates if Mason is unavailable)
• Mason bricks in bricks/ — real .dart files with Mustache variables for feature and storage scaffolding
• Freezed v3 fixes — added missing abstract keyword to 6 response classes
• module_generator.dart removed — fully superseded by spl_manager
• SPL.md added — full documentation for the SPL layer

Test plan

• flutter analyze — 0 errors
• dart run codegen/spl_manager.dart list — shows active features and SPL config
• dart run codegen/spl_manager.dart add <name> — scaffolds clean arch feature, DI auto-wired
• dart run codegen/spl_manager.dart disable <name> / enable <name> — feature moves to/from features_catalog/
• dart run codegen/spl_manager.dart storage set hive — switches storage backend, regenerates impl
• App runs and template features (authentication, onboarding, product, profile) work end-to-end