feat(properties): expenses tab with electricity+water chart

- expense_kind enum (utilities + maintenance/repair/cleaning/insurance/tax/rent/other)
- property_expenses table with optional link to a property_accounts row
  (preserves history via ON DELETE SET NULL)
- services/expenses.ts: CRUD + 12-month monthly series aggregation +
  year-to-date summary by kind
- /properties/[id]/expenses tab: inline SVG line chart for electricity +
  water last 12 months (no chart library), summary card, add/edit/delete
  inline with account linking when kind matches

src/lib/expenses.ts

@@ -0,0 +1,51 @@
+// Client-safe expense constants. Mirrors expense_kind in schema/_shared.ts.
+
+export type ExpenseKind =
+	| 'water'
+	| 'electricity'
+	| 'gas'
+	| 'internet'
+	| 'phone'
+	| 'cable'
+	| 'waste'
+	| 'maintenance'
+	| 'repair'
+	| 'cleaning'
+	| 'insurance'
+	| 'tax'
+	| 'rent'
+	| 'other';
+
+export const EXPENSE_KINDS: readonly ExpenseKind[] = [
+	'electricity',
+	'water',
+	'gas',
+	'internet',
+	'phone',
+	'cable',
+	'waste',
+	'maintenance',
+	'repair',
+	'cleaning',
+	'insurance',
+	'tax',
+	'rent',
+	'other'
+] as const;
+
+export const EXPENSE_KIND_LABEL: Record<ExpenseKind, string> = {
+	water: 'Water',
+	electricity: 'Electricity',
+	gas: 'Gas',
+	internet: 'Internet',
+	phone: 'Phone',
+	cable: 'Cable TV',
+	waste: 'Waste',
+	maintenance: 'Maintenance',
+	repair: 'Repair',
+	cleaning: 'Cleaning',
+	insurance: 'Insurance',
+	tax: 'Tax',
+	rent: 'Rent',
+	other: 'Other'
+};