Fix TypeScript compile errors blocking Docker build

- Add vite-env.d.ts for import.meta.env type support
- Remove unused imports: ChevronRight, useCallback (x2), today
- Silence unused attachments state read (keep setter for future use)
- Fix FloatManagement changeTinTargets reducer: drop unused k, fix v type

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/FloatManagement.tsx

@@ -1,4 +1,4 @@
-import { useState, useEffect, useCallback } from 'react'
+import { useState, useEffect } from 'react'
 import { Routes, Route, NavLink, Navigate, useNavigate } from 'react-router-dom'
 import { api } from '../api'
 import { PageHeader, Card, Btn } from '../components/Layout'
@@ -44,7 +44,7 @@ function FloatCountForm({ type }: { type: CountType }) {
   const totalCounted = denoms.reduce((s, d) => s + d.value * (denomQtys[d.value] ?? 0), 0)
   const totalReceipts = receipts.reduce((s, r) => s + (parseFloat(r.amount) || 0), 0)
   const targetAmount = type === 'petty_cash' ? pettyTarget : type === 'change_tin'
-    ? Object.entries(changeTinTargets).reduce((s, [k, v]) => s + parseFloat(v as string || '0'), 0)
+    ? Object.entries(changeTinTargets).reduce((s, [, v]) => s + (v || 0), 0)
     : 0
   const variance = type === 'petty_cash'
     ? totalCounted + totalReceipts - pettyTarget