feat(defects): add shared arktype defect input schema

Shared validation source for the DefectForm and /api/defects route
(Task 5): trimmed non-empty sectionId/verbatim and a uuid projectId.

shared/schemas/defect.ts

@@ -0,0 +1,19 @@
+import { type } from 'arktype'
+
+/**
+ * The user-supplied fields when filing a defect. `reporterEmail` and the
+ * timestamp are resolved server-side (getReporter / DB default), so they are
+ * not part of this input. This is the single source of validation truth shared
+ * by the DefectForm and the /api/defects route (wired in Task 5); import it via
+ * the `#shared` alias from either client or server.
+ */
+export const defectInput = type({
+  // section_id comes from the clicked board section — a non-empty slug.
+  sectionId: type('string.trim').to('string >= 1'),
+  // projectId references projects.id, a uuid.
+  projectId: 'string.uuid',
+  // The reporter's words — required, trimmed.
+  verbatim: type('string.trim').to('string >= 1'),
+})
+
+export type DefectInput = typeof defectInput.infer