feat: Enhance project and scenario creation with monitoring metrics

- Added monitoring metrics for project creation success and error handling in `ProjectRepository`.
- Implemented similar monitoring for scenario creation in `ScenarioRepository`.
- Refactored `run_monte_carlo` function in `simulation.py` to include timing and success/error metrics.
- Introduced new CSS styles for headers, alerts, and navigation buttons in `main.css` and `projects.css`.
- Created a new JavaScript file for navigation logic to handle chevron buttons.
- Updated HTML templates to include new navigation buttons and improved styling for buttons.
- Added tests for reporting service and routes to ensure proper functionality and access control.
- Removed unused imports and optimized existing test files for better clarity and performance.

models/performance_metric.py

@@ -0,0 +1,26 @@
+from __future__ import annotations
+
+from datetime import datetime
+from typing import Optional
+
+from sqlalchemy import Column, DateTime, Float, Integer, String
+from sqlalchemy.ext.declarative import declarative_base
+
+Base = declarative_base()
+
+
+class PerformanceMetric(Base):
+    __tablename__ = "performance_metrics"
+
+    id = Column(Integer, primary_key=True, index=True)
+    timestamp = Column(DateTime, default=datetime.utcnow, index=True)
+    metric_name = Column(String, index=True)
+    value = Column(Float)
+    labels = Column(String)  # JSON string of labels
+    endpoint = Column(String, index=True, nullable=True)
+    method = Column(String, nullable=True)
+    status_code = Column(Integer, nullable=True)
+    duration_seconds = Column(Float, nullable=True)
+
+    def __repr__(self) -> str:
+        return f"<PerformanceMetric(id={self.id}, name={self.metric_name}, value={self.value})>"