feat: replace quota input with amount-first UI and atomic quota adjustment

- Refactor token, redemption, and user quota inputs to prioritize monetary
  amount entry, with raw quota input collapsed by default
- Add atomic quota adjustment modal for users with add/subtract/override modes,
  bypassing batch update queue for immediate DB consistency
- Make user quota fields readonly in edit form; all modifications go through
  the dedicated adjust-quota modal via POST /api/user/manage
- Add DecreaseUserQuota `db` parameter for direct DB writes, matching
  IncreaseUserQuota behavior
- Support negative quota display in amount conversion helpers
- Add i18n keys for all new UI strings across all locales

web/src/helpers/quota.js

@@ -1,3 +1,21 @@
+/*
+Copyright (C) 2025 QuantumNous
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as
+published by the Free Software Foundation, either version 3 of the
+License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+For commercial licensing, please contact support@quantumnous.com
+*/
 import { getCurrencyConfig } from './render';
 
 export const getQuotaPerUnit = () => {
@@ -7,19 +25,23 @@ export const getQuotaPerUnit = () => {
 
 export const quotaToDisplayAmount = (quota) => {
   const q = Number(quota || 0);
-  if (!Number.isFinite(q) || q <= 0) return 0;
+  if (!Number.isFinite(q) || q === 0) return 0;
+  const sign = Math.sign(q);
+  const abs = Math.abs(q);
   const { type, rate } = getCurrencyConfig();
   if (type === 'TOKENS') return q;
-  const usd = q / getQuotaPerUnit();
-  if (type === 'USD') return usd;
-  return usd * (rate || 1);
+  const usd = abs / getQuotaPerUnit();
+  if (type === 'USD') return sign * usd;
+  return sign * usd * (rate || 1);
 };
 
 export const displayAmountToQuota = (amount) => {
   const val = Number(amount || 0);
-  if (!Number.isFinite(val) || val <= 0) return 0;
+  if (!Number.isFinite(val) || val === 0) return 0;
+  const sign = Math.sign(val);
+  const abs = Math.abs(val);
   const { type, rate } = getCurrencyConfig();
   if (type === 'TOKENS') return Math.round(val);
-  const usd = type === 'USD' ? val : val / (rate || 1);
-  return Math.round(usd * getQuotaPerUnit());
+  const usd = type === 'USD' ? abs : abs / (rate || 1);
+  return sign * Math.round(usd * getQuotaPerUnit());
 };