Upgrade Filament, Livewire, Laravel, Guzzle, and PHPUnit to latest secure major versions #866

Summary

Upgrade core framework and test/dependency packages to patched major versions to address known and potential security vulnerabilities and reduce exposure from unsupported versions.

Packages to upgrade

• Filament: 4.x → 5.x
• Livewire: 3.x → 4.x
• Laravel: 12.x → 13.x
• Guzzle: 7.x → 8.x
• PHPUnit: 11.x → 13.x

Why

• Mitigate security risks from older major versions.
• Ensure ongoing security patch coverage from upstream maintainers.
• Keep the stack aligned with supported ecosystem versions.

Scope

• Update composer.json constraints for all listed packages.
• Update lockfile and resolve dependency conflicts.
• Refactor application code/config where breaking changes require modifications.
• Update tests to align with new PHPUnit major version.
• Validate CI pipeline and application startup/runtime flows.

Acceptance Criteria

• All listed packages are upgraded to target major versions.
• composer install/composer update completes without vulnerability warnings attributable to old versions.
• Application boots successfully and critical user flows pass smoke tests.
• Test suite runs successfully on updated PHPUnit.
• CI passes on default branch with upgraded dependency set.

Implementation Notes

• Perform upgrades in a controlled sequence (framework first, then ecosystem/testing) to reduce conflict complexity.
• Capture and document required code changes for each major upgrade.
• If full upgrade cannot land in one PR, split into incremental PRs while preserving compatibility.

Risks

• Breaking API changes across multiple major upgrades.
• Transitive dependency incompatibilities.
• Test instability during PHPUnit migration.

Deliverables

• Updated dependency manifests (composer.json / lockfile).
• Code/config/test updates required for compatibility.
• Migration notes in PR description or docs for maintainers.