feat(projects): backend support for subject-level regions array (Plan 6 Task 3)

- Project model: +regions in fillable + cast via PostgresIntArray
  (custom Eloquent cast for PG INT[] — Laravel stock 'array' uses JSON
  which Postgres rejects on native INT[] columns)
- StoreProjectRequest / UpdateProjectRequest: drop region_mask/mode rules,
  add regions array validation (1..89 each, present/sometimes)
- ProjectService::create: dual-write — regions источник истины + legacy
  region_mask=255 + region_mode='include' для PhonePrefixService/LeadRouter
  compatibility (Plan 6.5 cleanup will remove dual-write)
- +5 Pest tests covering create/update/dual-write/validation rejection
- Drive-by: SchemaDeltaTest indexes pin 117 → 118 (Plan 6 v8.20 carryover
  from Task 1; should ideally have landed in Task 1 commit c487641)
- phpstan-baseline: +3 entries for Project::$regions until next ide-helper
  regen; existing Pest actingAs counts bumped 9→12 / 6→8 for new tests

Verified: Pest --parallel 747/744/3sk/0/0 (5 new tests pass +
SchemaDeltaTest now green), phpstan 0 errors, pint clean, gitleaks 0.

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

app/app/Http/Requests/StoreProjectRequest.php

@@ -22,8 +22,11 @@ class StoreProjectRequest extends FormRequest
             'name' => ['required', 'string', 'max:255'],
             'signal_type' => ['required', Rule::in(['site', 'call', 'sms'])],
             'daily_limit_target' => ['required', 'integer', 'min:1', 'max:10000'],
-            'region_mask' => ['required', 'integer', 'min:0'],
-            'region_mode' => ['required', Rule::in(['include', 'exclude'])],
+            // Plan 6: subject-level regions[] заменил region_mask/region_mode на API-уровне.
+            // Empty array = "вся РФ" (паритет с legacy region_mask=255 + region_mode='include').
+            // present = поле должно быть в payload (даже если []), enforces explicit choice.
+            'regions' => ['present', 'array'],
+            'regions.*' => ['integer', 'between:1,89'],
             'delivery_days_mask' => ['required', 'integer', 'min:1', 'max:127'],
         ];