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.controller.ts

@@ -0,0 +1,121 @@
+import {
+  Controller,
+  Post,
+  Get,
+  Body,
+  UseGuards,
+  Request,
+  Res,
+  BadRequestException,
+  UnauthorizedException,
+} from '@nestjs/common';
+import { ApiTags, ApiOperation, ApiBearerAuth } from '@nestjs/swagger';
+import { Throttle } from '@nestjs/throttler';
+import { JwtService } from '@nestjs/jwt';
+import { Response } from 'express';
+import { MfaService } from './mfa.service';
+import { AuthService } from './auth.service';
+import { JwtAuthGuard } from './guards/jwt-auth.guard';
+import { AllowViewer } from '../../common/decorators/allow-viewer.decorator';
+
+const COOKIE_NAME = 'ledgeriq_rt';
+const isProduction = process.env.NODE_ENV === 'production';
+
+@ApiTags('auth')
+@Controller('auth/mfa')
+export class MfaController {
+  constructor(
+    private mfaService: MfaService,
+    private authService: AuthService,
+    private jwtService: JwtService,
+  ) {}
+
+  @Post('setup')
+  @ApiOperation({ summary: 'Generate MFA setup (QR code + secret)' })
+  @ApiBearerAuth()
+  @UseGuards(JwtAuthGuard)
+  async setup(@Request() req: any) {
+    return this.mfaService.generateSetup(req.user.sub);
+  }
+
+  @Post('enable')
+  @ApiOperation({ summary: 'Enable MFA after verifying TOTP code' })
+  @ApiBearerAuth()
+  @UseGuards(JwtAuthGuard)
+  async enable(@Request() req: any, @Body() body: { token: string }) {
+    if (!body.token) throw new BadRequestException('TOTP code required');
+    return this.mfaService.enableMfa(req.user.sub, body.token);
+  }
+
+  @Post('verify')
+  @ApiOperation({ summary: 'Verify MFA during login flow' })
+  @Throttle({ default: { limit: 5, ttl: 60000 } })
+  async verify(
+    @Body() body: { mfaToken: string; token: string; useRecovery?: boolean },
+    @Res({ passthrough: true }) res: Response,
+  ) {
+    if (!body.mfaToken || !body.token) {
+      throw new BadRequestException('mfaToken and verification code required');
+    }
+
+    // Decode the MFA challenge token
+    let payload: any;
+    try {
+      payload = this.jwtService.verify(body.mfaToken);
+      if (payload.type !== 'mfa_challenge') throw new Error('Wrong token type');
+    } catch {
+      throw new UnauthorizedException('Invalid or expired MFA challenge');
+    }
+
+    const userId = payload.sub;
+    let verified = false;
+
+    if (body.useRecovery) {
+      verified = await this.mfaService.verifyRecoveryCode(userId, body.token);
+    } else {
+      verified = await this.mfaService.verifyMfa(userId, body.token);
+    }
+
+    if (!verified) {
+      throw new UnauthorizedException('Invalid verification code');
+    }
+
+    // MFA passed — issue full session
+    const result = await this.authService.completeMfaLogin(userId);
+    if (result.refreshToken) {
+      res.cookie(COOKIE_NAME, result.refreshToken, {
+        httpOnly: true,
+        secure: isProduction,
+        sameSite: 'strict',
+        path: '/api/auth',
+        maxAge: 30 * 24 * 60 * 60 * 1000,
+      });
+    }
+    const { refreshToken: _rt, ...response } = result;
+    return response;
+  }
+
+  @Post('disable')
+  @ApiOperation({ summary: 'Disable MFA (requires password)' })
+  @ApiBearerAuth()
+  @UseGuards(JwtAuthGuard)
+  async disable(@Request() req: any, @Body() body: { password: string }) {
+    if (!body.password) throw new BadRequestException('Password required to disable MFA');
+
+    // Verify password first
+    const user = await this.authService.validateUser(req.user.email, body.password);
+    if (!user) throw new UnauthorizedException('Invalid password');
+
+    await this.mfaService.disableMfa(req.user.sub);
+    return { success: true };
+  }
+
+  @Get('status')
+  @ApiOperation({ summary: 'Get MFA status' })
+  @ApiBearerAuth()
+  @UseGuards(JwtAuthGuard)
+  @AllowViewer()
+  async status(@Request() req: any) {
+    return this.mfaService.getStatus(req.user.sub);
+  }
+}