Replace all uses of `forceFill`, `forceCreate`, and `forceFill` with their
non-force equivalents across models, actions, controllers, and Livewire
components. Add explicit `$fillable` arrays to all affected Eloquent models
to enforce mass assignment protection.
Add ModelFillableCreationTest and ModelFillableRegressionTest to verify that
model creation respects fillable constraints and prevent regressions.
Clear `branches` and `total_branches_count` in `loadRepositories` to avoid stale branch data after repo refreshes. Update the Livewire view to use the shared loading button pattern for refresh/load actions, and expand feature coverage for repository refresh behavior and refresh button visibility.
