feat: Implement initial capex calculation feature

- Added CapexComponentInput, CapexParameters, CapexCalculationRequest, CapexCalculationResult, and related schemas for capex calculations.
- Introduced calculate_initial_capex function to aggregate capex components and compute totals and timelines.
- Created ProjectCapexRepository and ScenarioCapexRepository for managing capex snapshots in the database.
- Developed capex.html template for capturing and displaying initial capex data.
- Registered common Jinja2 filters for formatting currency and percentages.
- Implemented unit and integration tests for capex calculation functionality.
- Updated unit of work to include new repositories for capex management.

routes/template_filters.py

@@ -0,0 +1,95 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from typing import Any
+
+from fastapi.templating import Jinja2Templates
+
+
+def format_datetime(value: Any) -> str:
+    """Render datetime values consistently for templates."""
+    if not isinstance(value, datetime):
+        return ""
+    if value.tzinfo is None:
+        value = value.replace(tzinfo=timezone.utc)
+    return value.strftime("%Y-%m-%d %H:%M UTC")
+
+
+def currency_display(value: Any, currency_code: str | None) -> str:
+    """Format numeric values with currency context."""
+    if value is None:
+        return "—"
+    if isinstance(value, (int, float)):
+        formatted_value = f"{value:,.2f}"
+    else:
+        formatted_value = str(value)
+    if currency_code:
+        return f"{currency_code} {formatted_value}"
+    return formatted_value
+
+
+def format_metric(value: Any, metric_name: str, currency_code: str | None = None) -> str:
+    """Format metrics according to their semantic type."""
+    if value is None:
+        return "—"
+
+    currency_metrics = {
+        "npv",
+        "inflows",
+        "outflows",
+        "net",
+        "total_inflows",
+        "total_outflows",
+        "total_net",
+    }
+    if metric_name in currency_metrics and currency_code:
+        return currency_display(value, currency_code)
+
+    percentage_metrics = {"irr", "payback_period"}
+    if metric_name in percentage_metrics:
+        if isinstance(value, (int, float)):
+            return f"{value:.2f}%"
+        return f"{value}%"
+
+    if isinstance(value, (int, float)):
+        return f"{value:,.2f}"
+
+    return str(value)
+
+
+def percentage_display(value: Any) -> str:
+    """Format numeric values as percentages."""
+    if value is None:
+        return "—"
+    if isinstance(value, (int, float)):
+        return f"{value:.2f}%"
+    return f"{value}%"
+
+
+def period_display(value: Any) -> str:
+    """Format period values in years."""
+    if value is None:
+        return "—"
+    if isinstance(value, (int, float)):
+        if value == int(value):
+            return f"{int(value)} years"
+        return f"{value:.1f} years"
+    return str(value)
+
+
+def register_common_filters(templates: Jinja2Templates) -> None:
+    templates.env.filters["format_datetime"] = format_datetime
+    templates.env.filters["currency_display"] = currency_display
+    templates.env.filters["format_metric"] = format_metric
+    templates.env.filters["percentage_display"] = percentage_display
+    templates.env.filters["period_display"] = period_display
+
+
+__all__ = [
+    "format_datetime",
+    "currency_display",
+    "format_metric",
+    "percentage_display",
+    "period_display",
+    "register_common_filters",
+]