feat(forms): onboarding form/waiver step with required enforcement (Phase 4)

- scripts/027 (idempotent CHECK replace) + schema.sql Section 14: allow
  space_onboarding_steps.step_type = 'form'; referenced form id lives in
  the step's existing config.form_id (no new column)
- finishOnboarding: a required form step is satisfied when a submission
  for config.form_id by the member exists (any version — re-sign is
  non-blocking / auto-satisfy); fails open if the form is missing or
  unpublished so a misconfig cannot trap a member. Probe uses the
  service client (submissions are forms.manage-only under RLS)
- onboarding page enriches form steps with the published form def +
  prior-submission flag; onboarding-flow renders FormRenderer + waiver
  legal text/consent and submits via submitForm then marks the step done
- customize: forms fetched and threaded to the onboarding panel; new
  "+ Form step" button + form picker writing config.form_id
- validations/types/casts include 'form'; forms.test.ts +2
- docs: DATABASE_SCHEMA/DB_SCHEMA_MAP/API_REFERENCE/ARCHITECTURE/HANDOFF

287/287 tests, build exit 0. No deploy.

__tests__/forms.test.ts

@@ -5,6 +5,8 @@ import {
   submitFormSchema,
   formSchemaArray,
   formFieldSchema,
+  onboardingStepTypeSchema,
+  createOnboardingStepSchema,
 } from '@/lib/validations'
 import { parseFormSchema, validateAnswers, type FormField } from '@/lib/forms-schema'
 
@@ -110,6 +112,23 @@ describe('validateAnswers', () => {
   })
 })
 
+describe('onboarding form step (Phase 4)', () => {
+  it('onboardingStepTypeSchema accepts "form" and rejects unknown', () => {
+    expect(onboardingStepTypeSchema.safeParse('form').success).toBe(true)
+    expect(onboardingStepTypeSchema.safeParse('content').success).toBe(true)
+    expect(onboardingStepTypeSchema.safeParse('quiz').success).toBe(false)
+  })
+
+  it('createOnboardingStepSchema accepts a form step with a form_id config', () => {
+    const r = createOnboardingStepSchema.safeParse({
+      step_type: 'form',
+      title: 'Sign the liability waiver',
+      config: { form_id: '11111111-1111-1111-1111-111111111111' },
+    })
+    expect(r.success).toBe(true)
+  })
+})
+
 describe('parseFormSchema', () => {
   it('returns [] for malformed stored schema', () => {
     expect(parseFormSchema('not an array')).toEqual([])