feat: add ownership-costs feature capsule (refs #15)

- Create ownership_costs table for recurring vehicle costs
- Add backend feature capsule with types, repository, service, routes
- Update TCO calculation to use ownership_costs (with fallback to legacy vehicle fields)
- Add taxCosts and otherCosts to TCO response
- Create frontend ownership-costs feature with form, list, API, hooks
- Update TCODisplay to show all cost types

This implements a more flexible approach to tracking recurring ownership costs
(insurance, registration, tax, other) with explicit date ranges and optional
document association.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/features/vehicles/components/TCODisplay.tsx

@@ -121,6 +121,12 @@ export const TCODisplay: React.FC<TCODisplayProps> = ({ vehicleId, tcoEnabled })
           {tco.registrationCosts > 0 && (
             <div>Registration: {currencySymbol}{formatCurrency(tco.registrationCosts)}</div>
           )}
+          {tco.taxCosts > 0 && (
+            <div>Tax: {currencySymbol}{formatCurrency(tco.taxCosts)}</div>
+          )}
+          {tco.otherCosts > 0 && (
+            <div>Other: {currencySymbol}{formatCurrency(tco.otherCosts)}</div>
+          )}
           {tco.fuelCosts > 0 && (
             <div>Fuel: {currencySymbol}{formatCurrency(tco.fuelCosts)}</div>
           )}