feat(plans): Stage 3b — DB-driven gates for reviews/styling/limits

Make more plan rules read the admin-editable catalog instead of hardcoded values:
- Review reply gated by the `review_reply` feature (Starter+) — 403 if not in plan.
- Custom menu styling gated by `custom_menu_styling` (Starter+): only blocks an
  actual theme change, so a normal settings save re-sending the current theme is fine.
- Menu categories/items limits now read catalog.GetLimitsAsync (Free categories
  editable; message no longer hardcodes a number).
- Terminals limit reads the catalog (enforcement in TerminalRegistryService +
  the displayed max in TerminalsController).

Remaining (small): menu watermark (Free shows it, `watermark_removed` removes it —
needs the public-menu render), report-history (static ReportPlanGate) and AI-3D
routing — these already enforce the correct matrix values, just not yet editable.

86 tests pass; build clean.

src/Meezi.API/Services/TerminalRegistryService.cs

@@ -23,8 +23,15 @@ public class TerminalRegistryService : ITerminalRegistryService
 {
     private static readonly TimeSpan TerminalTtl = TimeSpan.FromDays(90);
     private readonly IConnectionMultiplexer _redis;
+    private readonly Meezi.Infrastructure.Services.Platform.IPlatformCatalogService _catalog;
 
-    public TerminalRegistryService(IConnectionMultiplexer redis) => _redis = redis;
+    public TerminalRegistryService(
+        IConnectionMultiplexer redis,
+        Meezi.Infrastructure.Services.Platform.IPlatformCatalogService catalog)
+    {
+        _redis = redis;
+        _catalog = catalog;
+    }
 
     public async Task<(bool Allowed, string? ErrorCode, string? Message)> RegisterAsync(
         string cafeId,
@@ -38,7 +45,7 @@ public class TerminalRegistryService : ITerminalRegistryService
         terminalId = terminalId.Trim();
         var db = _redis.GetDatabase();
         var setKey = $"terminals:{cafeId}";
-        var max = PlanLimits.MaxTerminals(tier);
+        var max = (await _catalog.GetLimitsAsync(tier, cancellationToken)).MaxTerminals;
 
         if (max == int.MaxValue)
         {