feat(phases): implement webhooks (6.1), email (7.1), user preferences (7.2)

- Phase 6.1: WebhookConfig model, CRUD router (/api/v1/webhooks, admin-only),
  dispatch_webhook() with HMAC signing; integrated into test validation,
  campaign completion, and MITRE sync job
- Phase 7.1: SMTP email service with send_test_validated_email,
  send_campaign_completed_email, send_new_mitre_techniques_email;
  notify_role_with_email() added to notification_service
- Phase 7.2: notification_preferences and jira_account_id on User model;
  PATCH /users/me/preferences endpoint; Alembic migrations b031phase6 and b032phase7

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

backend/app/config.py

@@ -70,6 +70,16 @@ class Settings(BaseSettings):
     COMPANY_NAME: str = "Organization"
     COMPANY_LOGO_PATH: str = "app/templates/reports/assets/logo.png"
 
+    # ── Email / SMTP ──────────────────────────────────────────────────
+    SMTP_ENABLED: bool = False
+    SMTP_HOST: str = ""
+    SMTP_PORT: int = 587
+    SMTP_USERNAME: str = ""
+    SMTP_PASSWORD: str = ""
+    SMTP_FROM_EMAIL: str = "aegis@company.com"
+    SMTP_USE_TLS: bool = True
+    PLATFORM_URL: str = "http://localhost:5173"  # base URL for links in emails
+
     # ── Scoring weights (must sum to 100) ────────────────────────────
     SCORING_WEIGHT_TESTS: int = 40
     SCORING_WEIGHT_DETECTION_RULES: int = 25