fix: only count preview branches toward the preview branch limit

The Limits page counted development branches toward the preview-branch
limit, showing inflated and sometimes over-limit values. Filter the count
on type PREVIEW with a parent environment to mirror checkBranchLimit.

Closes #4281

Author: carderne

.server-changes/fix-preview-branch-limit-count.md

@@ -0,0 +1,6 @@
+---
+area: webapp
+type: fix
+---
+
+The "Preview branches" usage on the Limits page now counts only preview branches, so it no longer includes development branches or show over-limit values.

apps/webapp/app/presenters/v3/LimitsPresenter.server.ts

@@ -151,11 +151,14 @@ export class LimitsPresenter extends BasePresenter {
       },
     });
 
-    // Get active branches count for this org (uses @@index([organizationId]))
+    // Get active preview branches count for this org (uses @@index([organizationId]))
+    // Mirror checkBranchLimit: only PREVIEW branches (exclude the branchable parent).
+    // DEVELOPMENT branches have a separate limit and must not be counted here.
     const activeBranchCount = await this._replica.runtimeEnvironment.count({
       where: {
         projectId,
-        branchName: {
+        type: "PREVIEW",
+        parentEnvironmentId: {
           not: null,
         },
         archivedAt: null,