Version 3 - (╯°□°)╯︵ ┻━┻

[hparadiz]

PR Summary

This PR completes the v3 ORM/runtime refactor and closes the remaining release-blocking cleanup around model configuration and backend support.

What Changed

• split the old MySQL-centric database layer into backend-aware runtime pieces:
  • Connections
  • StorageType
  • concrete MySQL and SQLite drivers
  • backend-specific query renderers
  • backend-specific schema writers
• introduced first-class SQLite support across config, runtime, query rendering, schema generation, and test execution
• extracted model read/hydration concerns into:
  • Factory
  • ModelMetadata
  • Instantiator
  • EventBinder
  • PrototypeRegistry
• extracted lifecycle behavior from ActiveRecord into handler classes for save/delete/destroy/before-save/after-save/cache clearing/exception handling
• reduced per-model boilerplate by making these optional for ordinary models:
  • $rootClass
  • $defaultClass
  • $subClasses
  • $singularNoun
  • $pluralNoun
• kept explicit metadata support for real polymorphic roots and synthetic test models that intentionally need separate model identities
• added v3 architecture documentation in docs/v3-architecture.md
• linked the new architecture doc from the README and added a minimal model example near the top
• fixed config override loading so config/db.dev.php is resolved relative to config/db.php

Why

The old architecture concentrated too much behavior in ActiveRecord and a single MySQL-oriented DB helper. This PR moves the framework toward explicit layers for:

• backend resolution
• query dialect selection
• schema generation
• model metadata
• hydration
• lifecycle orchestration

That makes the runtime easier to extend, gives SQLite real support instead of partial compatibility, and removes repetitive boilerplate from normal models.

Compatibility Notes

• normal models no longer need to declare subclass metadata or noun labels unless they are intentionally overriding defaults
• polymorphic roots like Media should still declare explicit subclass metadata
• special test doubles or synthetic models that need their own root identity should also keep explicit metadata

Verification

• composer test passes
• MySQL: OK (221 tests, 539 assertions)
• SQLite: OK (221 tests, 545 assertions)