feat(usage): add subscription quota windows per provider on /usage page

reads local claude and codex auth files server-side, calls provider
quota apis (anthropic oauth usage, chatgpt wham/usage), and surfaces
live usedPercent per window in ProviderQuotaCard with threshold fill colors

packages/shared/src/index.ts

@@ -189,6 +189,8 @@ export type {
   PluginJobRecord,
   PluginJobRunRecord,
   PluginWebhookDeliveryRecord,
+  QuotaWindow,
+  ProviderQuotaResult,
 } from "./types/index.js";
 
 export {

packages/shared/src/types/index.ts

@@ -66,6 +66,7 @@ export type {
   JoinRequest,
   InstanceUserRoleGrant,
 } from "./access.js";
+export type { QuotaWindow, ProviderQuotaResult } from "./quota.js";
 export type {
   CompanyPortabilityInclude,
   CompanyPortabilitySecretRequirement,

packages/shared/src/types/quota.ts

@@ -0,0 +1,22 @@
+/** a single rate-limit or usage window returned by a provider quota API */
+export interface QuotaWindow {
+  /** human label, e.g. "5h", "7d", "Sonnet 7d", "Credits" */
+  label: string;
+  /** percent of the window already consumed (0-100), null when not reported */
+  usedPercent: number | null;
+  /** iso timestamp when this window resets, null when not reported */
+  resetsAt: string | null;
+  /** free-form value label for credit-style windows, e.g. "$4.20 remaining" */
+  valueLabel: string | null;
+}
+
+/** result for one provider from the quota-windows endpoint */
+export interface ProviderQuotaResult {
+  /** provider slug, e.g. "anthropic", "openai" */
+  provider: string;
+  /** true when the fetch succeeded and windows is populated */
+  ok: boolean;
+  /** error message when ok is false */
+  error?: string;
+  windows: QuotaWindow[];
+}