fix(contracts) : hide contract phases entirely before RTT_START_DATE

EmployeeContractPhaseResolver now accepts the data-start date and filters
out phases whose endDate is strictly before it. No work-hour or absence
data exists before the application launch date, so legacy contract
periods that ended before that date would surface meaningless RTT/CP
figures in the phase picker.

For employees who joined long before the software (typical legacy 35h
contracts, in production since 2014), only the current phase remains
visible — which also collapses the picker (threshold ≥ 2 phases).

The Employee entity reads RTT_START_DATE from $_SERVER/$_ENV directly
since it has no DI. The resolver service is wired via services.yaml.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Entity/Employee.php

@@ -446,7 +446,10 @@ class Employee
     #[Groups(['employee:read'])]
     public function getContractPhases(): array
     {
-        $resolver = new EmployeeContractPhaseResolver();
+        // Read RTT_START_DATE directly here: the entity has no DI but must filter
+        // out contract phases that ended before the application's data start.
+        $rawDate  = $_SERVER['RTT_START_DATE'] ?? $_ENV['RTT_START_DATE'] ?? '';
+        $resolver = new EmployeeContractPhaseResolver(is_string($rawDate) ? $rawDate : '');
 
         return array_map(
             static fn (ContractPhase $phase): array => [