feat: production launch — email audit, team invites, security headers, router fixes

- Fix loyalty & monitoring router bugs (_get_router → named routers)
- Implement team invitation email with send_template + seed templates (en/fr/de)
- Add SecurityHeadersMiddleware (nosniff, HSTS, referrer-policy, permissions-policy)
- Build email audit admin page: service, schemas, API, page route, menu, i18n, HTML, JS
- Clean stale TODO in platform-menu-config.js
- Add 67 tests (unit + integration) covering all new functionality

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

app/modules/messaging/schemas/email.py

@@ -245,3 +245,74 @@ class EmailTestResponse(BaseModel):
     success: bool
     message: str
     email_log_id: int | None = None
+
+
+# =============================================================================
+# Email Log (Audit) Schemas
+# =============================================================================
+
+
+class EmailLogListItem(BaseModel):
+    """Compact email log item (no body content)."""
+
+    id: int
+    recipient_email: str
+    recipient_name: str | None = None
+    subject: str
+    status: str
+    template_code: str | None = None
+    provider: str | None = None
+    store_id: int | None = None
+    related_type: str | None = None
+    related_id: int | None = None
+    created_at: str | None = None
+    sent_at: str | None = None
+    error_message: str | None = None
+
+
+class EmailLogDetail(BaseModel):
+    """Full email log detail including body content."""
+
+    id: int
+    recipient_email: str
+    recipient_name: str | None = None
+    subject: str
+    status: str
+    template_code: str | None = None
+    provider: str | None = None
+    store_id: int | None = None
+    user_id: int | None = None
+    related_type: str | None = None
+    related_id: int | None = None
+    from_email: str | None = None
+    from_name: str | None = None
+    reply_to: str | None = None
+    body_html: str | None = None
+    body_text: str | None = None
+    error_message: str | None = None
+    retry_count: int = 0
+    provider_message_id: str | None = None
+    created_at: str | None = None
+    sent_at: str | None = None
+    delivered_at: str | None = None
+    opened_at: str | None = None
+    clicked_at: str | None = None
+    extra_data: str | None = None
+
+
+class EmailLogListResponse(BaseModel):
+    """Paginated email log list."""
+
+    items: list[EmailLogListItem]
+    total: int
+    page: int
+    per_page: int
+    total_pages: int
+
+
+class EmailLogStatsResponse(BaseModel):
+    """Email log statistics."""
+
+    by_status: dict[str, int] = Field(default_factory=dict)
+    by_template: dict[str, int] = Field(default_factory=dict)
+    total: int = 0