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.

tests/defect-schema.spec.ts

@@ -0,0 +1,29 @@
+import { describe, expect, it } from 'vitest'
+import { type } from 'arktype'
+import { defectInput } from '../shared/schemas/defect'
+
+const valid = {
+  sectionId: 'a4-flow',
+  projectId: '123e4567-e89b-12d3-a456-426614174000',
+  verbatim: 'The thing broke',
+}
+
+describe('defectInput schema', () => {
+  it('accepts a valid defect and trims verbatim', () => {
+    const out = defectInput({ ...valid, verbatim: '  hi  ' })
+    expect(out instanceof type.errors).toBe(false)
+    expect((out as typeof valid).verbatim).toBe('hi')
+  })
+
+  it('rejects empty verbatim', () => {
+    expect(defectInput({ ...valid, verbatim: '' }) instanceof type.errors).toBe(true)
+  })
+
+  it('rejects whitespace-only verbatim', () => {
+    expect(defectInput({ ...valid, verbatim: '   ' }) instanceof type.errors).toBe(true)
+  })
+
+  it('rejects a non-uuid projectId', () => {
+    expect(defectInput({ ...valid, projectId: 'not-a-uuid' }) instanceof type.errors).toBe(true)
+  })
+})