feat: SaaS onboarding, Stripe billing, MFA, SSO, passkeys, refresh tokens

Complete SaaS self-service onboarding sprint:

- Stripe-powered signup flow: pricing page → checkout → provisioning → activation
- Refresh token infrastructure: 1h access tokens + 30-day httpOnly cookie refresh
- TOTP MFA with QR setup, recovery codes, and login challenge flow
- Google + Azure AD SSO (conditional on env vars) with account linking
- WebAuthn passkey registration and passwordless login
- Guided onboarding checklist with server-side progress tracking
- Stubbed email service (console + DB logging, ready for real provider)
- Settings page with tabbed security settings (MFA, passkeys, linked accounts)
- Login page enhanced with MFA verification, SSO buttons, passkey login
- Database migration 015 with all new tables and columns
- Version bump to 2026.03.17

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

backend/src/modules/auth/mfa.service.ts

@@ -0,0 +1,154 @@
+import { Injectable, Logger, BadRequestException, UnauthorizedException } from '@nestjs/common';
+import { DataSource } from 'typeorm';
+import * as bcrypt from 'bcryptjs';
+import { generateSecret, generateURI, verifySync } from 'otplib';
+import * as QRCode from 'qrcode';
+import { randomBytes } from 'crypto';
+
+@Injectable()
+export class MfaService {
+  private readonly logger = new Logger(MfaService.name);
+
+  constructor(private dataSource: DataSource) {}
+
+  /**
+   * Generate MFA setup data (secret + QR code) for a user.
+   */
+  async generateSetup(userId: string): Promise<{ secret: string; qrDataUrl: string; otpauthUrl: string }> {
+    const userRows = await this.dataSource.query(
+      `SELECT email, mfa_enabled FROM shared.users WHERE id = $1`,
+      [userId],
+    );
+    if (userRows.length === 0) throw new BadRequestException('User not found');
+
+    const secret = generateSecret();
+    const otpauthUrl = generateURI({ secret, issuer: 'HOA LedgerIQ', label: userRows[0].email });
+    const qrDataUrl = await QRCode.toDataURL(otpauthUrl);
+
+    // Store the secret temporarily (not verified yet)
+    await this.dataSource.query(
+      `UPDATE shared.users SET mfa_secret = $1, updated_at = NOW() WHERE id = $2`,
+      [secret, userId],
+    );
+
+    return { secret, qrDataUrl, otpauthUrl };
+  }
+
+  /**
+   * Enable MFA after verifying the initial TOTP code.
+   * Returns recovery codes.
+   */
+  async enableMfa(userId: string, token: string): Promise<{ recoveryCodes: string[] }> {
+    const userRows = await this.dataSource.query(
+      `SELECT mfa_secret, mfa_enabled FROM shared.users WHERE id = $1`,
+      [userId],
+    );
+    if (userRows.length === 0) throw new BadRequestException('User not found');
+    if (!userRows[0].mfa_secret) throw new BadRequestException('MFA setup not initiated');
+    if (userRows[0].mfa_enabled) throw new BadRequestException('MFA is already enabled');
+
+    // Verify the token
+    const result = verifySync({ token, secret: userRows[0].mfa_secret });
+    if (!result.valid) throw new BadRequestException('Invalid verification code');
+
+    // Generate recovery codes
+    const recoveryCodes = Array.from({ length: 10 }, () =>
+      randomBytes(4).toString('hex').toUpperCase(),
+    );
+
+    // Hash recovery codes for storage
+    const hashedCodes = await Promise.all(
+      recoveryCodes.map((code) => bcrypt.hash(code, 10)),
+    );
+
+    // Enable MFA
+    await this.dataSource.query(
+      `UPDATE shared.users SET
+        mfa_enabled = true,
+        totp_verified_at = NOW(),
+        recovery_codes = $1,
+        updated_at = NOW()
+       WHERE id = $2`,
+      [JSON.stringify(hashedCodes), userId],
+    );
+
+    this.logger.log(`MFA enabled for user ${userId}`);
+    return { recoveryCodes };
+  }
+
+  /**
+   * Verify a TOTP code during login.
+   */
+  async verifyMfa(userId: string, token: string): Promise<boolean> {
+    const userRows = await this.dataSource.query(
+      `SELECT mfa_secret, mfa_enabled FROM shared.users WHERE id = $1`,
+      [userId],
+    );
+    if (userRows.length === 0 || !userRows[0].mfa_enabled) return false;
+
+    const result = verifySync({ token, secret: userRows[0].mfa_secret });
+    return result.valid;
+  }
+
+  /**
+   * Verify a recovery code (consumes it on success).
+   */
+  async verifyRecoveryCode(userId: string, code: string): Promise<boolean> {
+    const userRows = await this.dataSource.query(
+      `SELECT recovery_codes FROM shared.users WHERE id = $1`,
+      [userId],
+    );
+    if (userRows.length === 0 || !userRows[0].recovery_codes) return false;
+
+    const hashedCodes: string[] = JSON.parse(userRows[0].recovery_codes);
+
+    for (let i = 0; i < hashedCodes.length; i++) {
+      const match = await bcrypt.compare(code.toUpperCase(), hashedCodes[i]);
+      if (match) {
+        // Remove the used code
+        hashedCodes.splice(i, 1);
+        await this.dataSource.query(
+          `UPDATE shared.users SET recovery_codes = $1, updated_at = NOW() WHERE id = $2`,
+          [JSON.stringify(hashedCodes), userId],
+        );
+        this.logger.log(`Recovery code used for user ${userId}`);
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * Disable MFA (requires password verification done by caller).
+   */
+  async disableMfa(userId: string): Promise<void> {
+    await this.dataSource.query(
+      `UPDATE shared.users SET
+        mfa_enabled = false,
+        mfa_secret = NULL,
+        totp_verified_at = NULL,
+        recovery_codes = NULL,
+        updated_at = NOW()
+       WHERE id = $1`,
+      [userId],
+    );
+    this.logger.log(`MFA disabled for user ${userId}`);
+  }
+
+  /**
+   * Get MFA status for a user.
+   */
+  async getStatus(userId: string): Promise<{ enabled: boolean; hasRecoveryCodes: boolean }> {
+    const rows = await this.dataSource.query(
+      `SELECT mfa_enabled, recovery_codes FROM shared.users WHERE id = $1`,
+      [userId],
+    );
+    if (rows.length === 0) return { enabled: false, hasRecoveryCodes: false };
+
+    return {
+      enabled: rows[0].mfa_enabled || false,
+      hasRecoveryCodes: !!rows[0].recovery_codes && JSON.parse(rows[0].recovery_codes || '[]').length > 0,
+    };
+  }
+}