fix(subscription): plan comparison + checkout read the live plan catalog

The merchant plan page hard-coded 4 tiers, prices and a feature matrix
that drifted from the admin-editable platform catalog (Starter tier
missing, stale prices/features). PlanComparison and CheckoutScreen now
consume /platform/plans + new /platform/features-catalog:

- columns = active plans by SortOrder (incl. Starter), names from
  DisplayNameFa/En, prices from MonthlyPriceToman
- limit rows from PlanLimitsData (int.MaxValue → "نامحدود")
- feature rows from the feature catalog, ticked via FeatureKeys
- checkout validates the ?plan= param against isBillableOnline and
  prices from the catalog — no more client-side price constants

fa/en/ar limit-row labels added.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/Meezi.API/Controllers/CafePlatformController.cs

@@ -36,4 +36,13 @@ public class CafePlatformController : CafeApiControllerBase
         var plans = await _catalog.GetPlansAsync(cancellationToken);
         return Ok(new ApiResponse<object>(true, plans));
     }
+
+    /// <summary>Feature catalog (key → display name / module group) so clients can
+    /// label the FeatureKeys returned by the plans endpoint.</summary>
+    [HttpGet("features-catalog")]
+    public async Task<IActionResult> GetFeaturesCatalog(CancellationToken cancellationToken)
+    {
+        var features = await _catalog.GetFeaturesAsync(cancellationToken);
+        return Ok(new ApiResponse<object>(true, features));
+    }
 }