feat!: API keys actually gate the gateway — auth, attribution, rate limits, budgets

The office-readiness audit found the foundation missing: configured API keys
were decorative. Any bearer — or none — passed every model endpoint, per-key
rate limits existed only in the form, and all real traffic was recorded as
"anonymous", leaving the per-key spend table permanently blank.

A middleware on the model surface (/v1/*, /route, /mcp) now enforces keys:
- no keys configured → open mode as before (the console already warns);
- keys exist → Bearer or x-api-key must match (401 invalid_api_key);
- per-key rate_per_min → fixed one-minute window, 429 with Retry-After;
- NEW per-key monthly_budget_usd → 429 insufficient_quota once the account's
  month-to-date spend crosses the ceiling;
- the matched account rides the request into stats — the keys table's spend
  columns finally see real traffic.

Month-to-date spend is tracked per account in stats and persisted in the
totals sidecar with a watermark (no double counting across restarts). The
key dialog gains a budget field; the table shows "budget $N/mo" in red once
exhausted. All verified live: 401 wrong/missing key, 200 + attribution with
the right key, 429 + Retry-After over the limit, 429 insufficient_quota on
the second request past a $0.000001 budget.

Also: the dashboard shows the OpenRouter credit balance (GET
/api/v1/credits via the stored key, cached 5 min, hidden without a key, red
under $5 — live: $16.18), the server drains connections on Ctrl-C instead
of dropping them, request bodies are capped at 32 MB, and docs/DEPLOY(.ru)
cover office deployment: systemd/launchd/Windows service, nginx/caddy TLS,
security checklist, backups. 10 strings ×7 languages.

web/js/i18n/de.js

@@ -639,4 +639,8 @@ export default {
   "settings.cache.entries": "Einträge",
   "settings.cache.hits": "Treffer",
   "settings.cache.saved": "gespart",
+  "keys.form.budget": "Monatsbudget, $ (0 = unbegrenzt)",
+  "keys.form.budgetHint": "Überschreiten die Monatsausgaben des Kontos die Grenze, werden Anfragen mit 429 insufficient_quota abgelehnt.",
+  "keys.budgetOf": "Budget {b}/Mon.",
+  "dash.kpi.orBalance": "OpenRouter-Guthaben",
 };

web/js/i18n/en.js

@@ -632,4 +632,8 @@ export default {
   "settings.cache.entries": "entries",
   "settings.cache.hits": "hits",
   "settings.cache.saved": "saved",
+  "keys.form.budget": "Monthly budget, $ (0 = unlimited)",
+  "keys.form.budgetHint": "Requests are rejected with 429 insufficient_quota once the account's month-to-date spend crosses this.",
+  "keys.budgetOf": "budget {b}/mo",
+  "dash.kpi.orBalance": "OpenRouter balance",
 };

web/js/i18n/es.js

@@ -639,4 +639,8 @@ export default {
   "settings.cache.entries": "entradas",
   "settings.cache.hits": "aciertos",
   "settings.cache.saved": "ahorrado",
+  "keys.form.budget": "Presupuesto mensual, $ (0 = sin límite)",
+  "keys.form.budgetHint": "Cuando el gasto del mes supera el techo, las peticiones se rechazan con 429 insufficient_quota.",
+  "keys.budgetOf": "presupuesto {b}/mes",
+  "dash.kpi.orBalance": "Saldo OpenRouter",
 };

web/js/i18n/fr.js

@@ -639,4 +639,8 @@ export default {
   "settings.cache.entries": "entrées",
   "settings.cache.hits": "hits",
   "settings.cache.saved": "économisé",
+  "keys.form.budget": "Budget mensuel, $ (0 = illimité)",
+  "keys.form.budgetHint": "Quand les dépenses du mois dépassent le plafond, les requêtes sont rejetées avec 429 insufficient_quota.",
+  "keys.budgetOf": "budget {b}/mois",
+  "dash.kpi.orBalance": "Solde OpenRouter",
 };

web/js/i18n/ru.js

@@ -631,4 +631,8 @@ export default {
   "settings.cache.entries": "записей",
   "settings.cache.hits": "попаданий",
   "settings.cache.saved": "сэкономлено",
+  "keys.form.budget": "Бюджет в месяц, $ (0 = без лимита)",
+  "keys.form.budgetHint": "Когда траты аккаунта за месяц превысят потолок, запросы отклоняются с 429 insufficient_quota.",
+  "keys.budgetOf": "бюджет {b}/мес",
+  "dash.kpi.orBalance": "Баланс OpenRouter",
 };

web/js/i18n/tr.js

@@ -639,4 +639,8 @@ export default {
   "settings.cache.entries": "kayıt",
   "settings.cache.hits": "isabet",
   "settings.cache.saved": "tasarruf",
+  "keys.form.budget": "Aylık bütçe, $ (0 = sınırsız)",
+  "keys.form.budgetHint": "Hesabın aylık harcaması tavanı aşınca istekler 429 insufficient_quota ile reddedilir.",
+  "keys.budgetOf": "bütçe {b}/ay",
+  "dash.kpi.orBalance": "OpenRouter bakiyesi",
 };

web/js/i18n/zh.js

@@ -639,4 +639,8 @@ export default {
   "settings.cache.entries": "条目",
   "settings.cache.hits": "命中",
   "settings.cache.saved": "已节省",
+  "keys.form.budget": "每月预算，$（0 = 不限）",
+  "keys.form.budgetHint": "当账户当月支出超过上限时，请求将被拒绝并返回 429 insufficient_quota。",
+  "keys.budgetOf": "预算 {b}/月",
+  "dash.kpi.orBalance": "OpenRouter 余额",
 };