Fix zod imports with ast-grep namespace import rule

Applied ast-grep rule to convert named zod imports to namespace imports
across the api-contract package for consistency.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.ast-grep/rule-tests/__snapshots__/zod-namespace-import-snapshot.yml

@@ -0,0 +1,20 @@
+id: zod-namespace-import
+snapshots:
+  ? |
+    import { z } from "zod";
+  : fixed: |
+      import * as z from "zod"
+    labels:
+    - source: import { z } from "zod";
+      style: primary
+      start: 0
+      end: 24
+  ? |
+    import { z, ZodError } from "zod";
+  : fixed: |
+      import * as z from "zod"
+    labels:
+    - source: import { z, ZodError } from "zod";
+      style: primary
+      start: 0
+      end: 34

.ast-grep/rule-tests/zod-namespace-import-test.yml

@@ -0,0 +1,13 @@
+id: zod-namespace-import
+valid:
+  - |
+    import * as z from "zod";
+  - |
+    import * as z from "zod";
+    const schema = z.object({ name: z.string() });
+
+invalid:
+  - |
+    import { z } from "zod";
+  - |
+    import { z, ZodError } from "zod";

.ast-grep/rules/zod-namespace-import.yml

@@ -0,0 +1,11 @@
+id: zod-namespace-import
+language: typescript
+severity: error
+message: Use namespace import for zod - `import * as z from "zod"` instead of named import
+note: |
+  Named imports from zod (e.g., `import { z } from "zod"`) should be replaced
+  with namespace imports (`import * as z from "zod"`) for consistency and to
+  ensure all zod utilities are available under the `z` namespace.
+rule:
+  pattern: import { $$$IMPORTS } from "zod"
+fix: import * as z from "zod";