feat: add Terms & Conditions checkbox to signup (refs #4)

- Add terms_agreements table for legal audit trail
- Create terms-agreement feature capsule with repository
- Modify signup to create terms agreement atomically
- Add checkbox with PDF link to SignupForm
- Capture IP, User-Agent, terms version, content hash
- Update CLAUDE.md documentation index

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/src/features/auth/domain/auth.service.ts

@@ -5,6 +5,8 @@
 
 import { auth0ManagementClient } from '../../../core/auth/auth0-management.client';
 import { UserProfileRepository } from '../../user-profile/data/user-profile.repository';
+import { TermsAgreementRepository } from '../../terms-agreement/data/terms-agreement.repository';
+import { pool } from '../../../core/config/database';
 import { logger } from '../../../core/logging/logger';
 import {
   SignupRequest,
@@ -13,17 +15,21 @@ import {
   ResendVerificationResponse,
   SecurityStatusResponse,
   PasswordResetResponse,
+  TermsData,
 } from './auth.types';
 
 export class AuthService {
-  constructor(private userProfileRepository: UserProfileRepository) {}
+  constructor(
+    private userProfileRepository: UserProfileRepository,
+    private termsAgreementRepository: TermsAgreementRepository
+  ) {}
 
   /**
    * Create a new user account
    * 1. Create user in Auth0 (which automatically sends verification email)
-   * 2. Create local user profile with emailVerified=false
+   * 2. Create local user profile and terms agreement atomically
    */
-  async signup(request: SignupRequest): Promise<SignupResponse> {
+  async signup(request: SignupRequest, termsData: TermsData): Promise<SignupResponse> {
     const { email, password } = request;
 
     try {
@@ -36,14 +42,42 @@ export class AuthService {
 
       logger.info('Auth0 user created', { auth0UserId, email });
 
-      // Create local user profile
-      const userProfile = await this.userProfileRepository.create(
-        auth0UserId,
-        email,
-        undefined // displayName is optional
-      );
+      // Create local user profile and terms agreement in a transaction
+      const client = await pool.connect();
+      try {
+        await client.query('BEGIN');
 
-      logger.info('User profile created', { userId: userProfile.id, email });
+        // Create user profile
+        const profileQuery = `
+          INSERT INTO user_profiles (auth0_sub, email, subscription_tier)
+          VALUES ($1, $2, 'free')
+          RETURNING id
+        `;
+        const profileResult = await client.query(profileQuery, [auth0UserId, email]);
+        const profileId = profileResult.rows[0].id;
+
+        logger.info('User profile created', { userId: profileId, email });
+
+        // Create terms agreement
+        await this.termsAgreementRepository.create({
+          userId: auth0UserId,
+          ipAddress: termsData.ipAddress,
+          userAgent: termsData.userAgent,
+          termsVersion: termsData.termsVersion,
+          termsUrl: termsData.termsUrl,
+          termsContentHash: termsData.termsContentHash,
+        }, client);
+
+        logger.info('Terms agreement created', { userId: auth0UserId });
+
+        await client.query('COMMIT');
+      } catch (error) {
+        await client.query('ROLLBACK');
+        logger.error('Transaction failed, rolling back', { error, email });
+        throw error;
+      } finally {
+        client.release();
+      }
 
       return {
         userId: auth0UserId,