feat(db): drop users.consentGiven/consentAt (ADR-0014 step 8)

Backfills consent_given=1 rows into user_consents as data:core before
dropping the legacy columns. auth.ts now writes user_consents on signup;
POST /consent writes user_consents; admin/user routes cleaned of the old
fields. Migration is idempotent — DROP COLUMN is wrapped in try/catch so
it no-ops on fresh DBs that never had the columns.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/api/src/routes/__tests__/profile.test.ts

@@ -72,7 +72,6 @@ beforeAll(async () => {
     name: 'Alice',
     image: null,
     role: 'user',
-    consentGiven: false,
     tone: 'direct',
     tipKindsJson: JSON.stringify(['task', 'advice']),
     createdAt: NOW,
@@ -90,13 +89,6 @@ describe('GET /api/profile', () => {
     expect(body.contexts).toEqual([]);
   });
 
-  it('surfaces legacy consentGiven as data:core when no consent row exists', async () => {
-    await testDb.update(users).set({ consentGiven: true, consentAt: NOW });
-    const res = await c('GET', '/api/profile');
-    expect((res.body as any).consents['data:core']).toMatchObject({ revokedAt: null });
-    await testDb.update(users).set({ consentGiven: false });
-  });
-
   it('includes prefs grouped by scope', async () => {
     await testDb.insert(userPreferences).values([
       { userId: 'user-1', scope: 'orchestrator', key: 'quietHours', valueJson: '"22:00-07:00"', source: 'user', updatedAt: NOW },