Use DoctrineORM instead of unmaintained FluentPDO

[Vitexus]

Motivation

FluentPDO is no longer maintained and lacks features and robustness required for modern PHP applications. DoctrineORM is a widely adopted, well-maintained ORM that will improve maintainability, testability, and future-proofing of the MultiFlexi project.

Migration Plan

• Add DoctrineORM to composer dependencies.
• Create Doctrine entities for all models currently using FluentPDO.
• Refactor all model classes to use DoctrineORM for database operations.
• Update CLI commands, backend logic, and daemons to use the new ORM.
• Update and expand unit tests to cover new ORM logic.
• Update documentation to reflect the new ORM usage.
• Remove FluentPDO and related code.

Impact Analysis

• All database access code will be refactored.
• Potential for minor behavioral changes in edge cases.
• Improved maintainability, security, and performance.
• All tests and documentation must be updated.

Acceptance Criteria

• All features work as before, but using DoctrineORM.
• No FluentPDO code remains.
• All tests pass.
• Documentation is updated.

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This issue tracks the migration from FluentPDO to DoctrineORM for the MultiFlexi project.