feat: finalize managed environment cutover seal (#354)
## Summary
- replace the remaining workspace overview tenant-first copy with environment-first wording in the builder, Blade view, and focused feature assertions
- add the Spec 299 workspace overview browser smoke and the final cutover audit documenting fixed copy, clean runtime scans, and allowed internal/provider/regression-guard `Tenant` references
- add the Spec 299 spec package (`spec.md`, `plan.md`, `tasks.md`, checklist, audit) to close the managed-environment cutover with an explicit final seal decision
## Validation
- `cd apps/platform && ./vendor/bin/sail artisan test --compact tests/Feature/Filament/WorkspaceOverviewContentTest.php tests/Feature/Filament/AdminHomeRedirectsToChooseTenantWhenWorkspaceSelectedTest.php tests/Feature/Filament/WorkspaceOverviewEmptyStatesTest.php`
- `cd apps/platform && ./vendor/bin/sail artisan test --compact tests/Feature/Guards/NoLegacyTenantPanelRuntimeTest.php tests/Feature/Guards/NoActiveTenantResourceRoutesTest.php tests/Feature/Guards/ManagedEnvironmentCanonicalRouteContractTest.php tests/Feature/Filament/PanelNavigationSegregationTest.php tests/Feature/Workspaces/WorkspaceIntendedUrlLegacyRejectionTest.php tests/Feature/ProviderConnections/LegacyRedirectTest.php tests/Feature/ManagedEnvironment/LegacyTenantCoreGuardTest.php tests/Feature/Spec080WorkspaceManagedTenantAdminMigrationTest.php tests/Feature/Filament/ManagedEnvironmentAccessScopeManagementTest.php tests/Feature/Rbac/ProviderConnectionWorkspaceFirstPolicyTest.php`
- `cd apps/platform && ./vendor/bin/sail artisan test --compact tests/Feature/Guards`
- `cd apps/platform && ./vendor/bin/sail artisan test --compact tests/Feature/Workspaces`
- `cd apps/platform && ./vendor/bin/sail artisan test --compact tests/Feature/ProviderConnections`
- `cd apps/platform && ./vendor/bin/sail artisan test --compact tests/Feature/RequiredPermissions`
- `cd apps/platform && ./vendor/bin/sail artisan test --compact tests/Feature/Filament`
- `cd apps/platform && ./vendor/bin/sail artisan test --compact tests/Browser/Spec299WorkspaceOverviewCutoverSealSmokeTest.php`
- `cd apps/platform && ./vendor/bin/sail bin pint --dirty --format agent`
- `git diff --check`
## Notes
- Filament remains on Livewire v4.
- Provider registration remains in `apps/platform/bootstrap/providers.php`.
- No new panel provider or asset-strategy changes are included.
- Remaining technical `Tenant` references are documented in `specs/299-managed-environment-cutover-final-seal/final-cutover-audit.md`.
Co-authored-by: Ahmed Darrazi <ahmed.darrazi@live.de>
Reviewed-on: #354
ahmido
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