chore: add Biome for lint and fix all lint errors

- Install @biomejs/biome as devDependency at root
- Configure biome.json with 2-space indent, double quotes, Tailwind CSS support
- Add lint/lint:fix/format/format:fix scripts to root and app package.json
- Fix noNonNullAssertion: env vars extracted to variables with suppression, <div role=button> replaced with <button>
- Fix noUnusedVariables: remove unused destructured vars
- Fix useIterableCallbackReturn: arrow functions with block body
- Fix noExplicitAny: recharts Tooltip formatters
- Fix noLabelWithoutControl: add htmlFor+id or use <span> for non-input labels
- Fix noStaticElementInteractions/useKeyWithClickEvents: role+keyboard events for overlays
- Fix noArrayIndexKey: use error string as key
- Fix CSS parse: enable tailwindDirectives parser
- Normalize formatting across 80 files with biome check --write

apps/backend/src/modules/expenses/handlers/getMonthlyPayedTotal.ts

@@ -2,8 +2,14 @@ import type { Context } from "hono";
 import { getMonthlyPayedTotal } from "../expenses.service";
 
 export async function getMonthlyPayedTotalHandler(c: Context) {
-  const year = parseInt(c.req.query("year") ?? String(new Date().getUTCFullYear()), 10);
-  const month = parseInt(c.req.query("month") ?? String(new Date().getUTCMonth() + 1), 10);
+  const year = parseInt(
+    c.req.query("year") ?? String(new Date().getUTCFullYear()),
+    10,
+  );
+  const month = parseInt(
+    c.req.query("month") ?? String(new Date().getUTCMonth() + 1),
+    10,
+  );
   const result = await getMonthlyPayedTotal(year, month);
   return c.json(result);
 }