Add detailed SQLAlchemy models, navigation metadata, enumerations, Pydantic schemas, monitoring, and auditing documentation

- Introduced SQLAlchemy models for user management, project management, financial inputs, and pricing configuration.
- Created navigation metadata tables for sidebar and top-level menus.
- Cataloged enumerations used across ORM models and Pydantic schemas.
- Documented Pydantic schemas for API request/response validation, including authentication, project, scenario, import, and export schemas.
- Added monitoring and auditing tables for performance metrics and import/export logs.
- Updated security documentation to reflect changes in data model references.

architecture/08_concepts/02_data_model/05_monitoring.md

@@ -0,0 +1,41 @@
+# Monitoring and Auditing
+
+This page documents the monitoring- and auditing-related tables that were previously embedded in `02_data_model.md`. Separating them keeps operational telemetry isolated from the core project/scenario data model reference.
+
+## PerformanceMetric
+
+Tracks API performance metrics used by the monitoring pipeline.
+
+**Table:** `performance_metrics`
+
+| Attribute        | Type         | Description           |
+| ---------------- | ------------ | --------------------- |
+| id               | Integer (PK) | Primary key           |
+| timestamp        | DateTime     | Metric timestamp      |
+| metric_name      | String       | Metric name           |
+| value            | Float        | Metric value          |
+| labels           | String       | JSON string of labels |
+| endpoint         | String       | API endpoint          |
+| method           | String       | HTTP method           |
+| status_code      | Integer      | HTTP status code      |
+| duration_seconds | Float        | Request duration      |
+
+## ImportExportLog
+
+Audit log for import and export operations initiated by users.
+
+**Table:** `import_export_logs`
+
+| Attribute  | Type                    | Description                           |
+| ---------- | ----------------------- | ------------------------------------- |
+| id         | Integer (PK)            | Primary key                           |
+| action     | String(32)              | Action type (preview, commit, export) |
+| dataset    | String(32)              | Dataset type (projects, scenarios)    |
+| status     | String(16)              | Operation status                      |
+| filename   | String(255)             | File name                             |
+| row_count  | Integer                 | Number of rows                        |
+| detail     | Text                    | Additional details                    |
+| user_id    | Integer (FK → users.id) | User foreign key                      |
+| created_at | DateTime                | Creation timestamp                    |
+
+These tables power telemetry dashboards and audit trails but are not exposed via public API endpoints.